text stringlengths 81 47k | source stringlengths 59 147 |
|---|---|
Question: <p>I wonder how to properly write the motion equations for the inverted pendulum on a cart in case of overdamped dynamics. Imagine the system <a href="http://en.wikipedia.org/wiki/Inverted_pendulum#Inverted_pendulum_on_a_cart" rel="nofollow noreferrer">illustrated in Wikipedia</a> placed in a liquid with high... | https://physics.stackexchange.com/questions/69438/dynamics-of-controlled-overdamped-inverted-pendulum |
Question: <p>Let us say we have a mighty man crossing a bridge, carrying 4 bags of concrete, each of which weighs 50 pounds. </p>
<p>Let us say, for the sake of the argument, that the mighty man himself weighs 300 pounds.</p>
<p>The support capacity of the bridge $x$ is less than the 500 pounds they weigh together -... | https://physics.stackexchange.com/questions/69984/the-mighty-man-and-the-bridge |
Question: <p>I suspect this has been asked here before, but I didn't find anything using Search.</p>
<p>Why is Newton's second law only second-order in position? For instance, could there exist higher-order masses $m_i$ with</p>
<p>$$F(x) = m\ddot{x} + \sum_{i=3}^{\infty} m_i x^{(i)}?$$</p>
<p>Are there theoretical ... | https://physics.stackexchange.com/questions/93659/why-doesnt-newtons-second-law-include-higher-order-mass |
Question: <p>I've posed the question in this particular way to avoid the ambiguity usually found in the posing of the "<a href="http://pogue.blogs.nytimes.com/2006/12/11/the-airplane-treadmill-conundrum/" rel="nofollow noreferrer">airplane on a treadmill</a>" puzzle, <a href="https://physics.stackexchange.com/questions... | https://physics.stackexchange.com/questions/32325/is-it-possible-to-control-a-treadmills-tread-speed-such-that-a-plane-on-the-tre |
Question: <p>Looking around it appears that bricks, through history, have been constructed in cuboid form i.e. with six faces at right-angles to each other. This is also apparently the case with stone construction too - six-sided volumes.</p>
<p>Is the cuboid form the most efficient form to bear load? </p>
<p>How do ... | https://physics.stackexchange.com/questions/32911/why-are-bricks-typically-constructed-to-have-six-faces-at-or-near-right-angles |
Question: <p>We consider a system of "n" particles whose total energy E and net momentum $\vec{P}$ are fixed are fixed.There no net force on the system(assumed)</p>
<p>$$\Sigma \epsilon_i= E$$
$$\Sigma\vec{p_i}=\vec{P}$$
For an individual particle its momentnum and energy remain constant for the time $\tau$,the relaxa... | https://physics.stackexchange.com/questions/34447/on-the-discretization-of-energy-levels |
Question: <blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="https://physics.stackexchange.com/questions/1639/whats-the-difference-between-running-up-a-hill-and-running-up-an-inclined-tread">What's the difference between running up a hill and running up an inclined treadmill?</a> </p>
</blockquo... | https://physics.stackexchange.com/questions/35313/how-does-a-treadmill-incline-mechanism-work |
Question: <p>What's a physical meaning of, for example, complex part of the solution for coordinate change of the anharmonic oscillator?
Why after substitute (for diff. equation solve) for real x we can earn $x = Re(z) + iIm(z)$? It's because of substitute?</p>
Answer: <p>When we wish to solve a differential equation ... | https://physics.stackexchange.com/questions/35805/complex-part-of-the-solution-for-physical-values |
Question: <blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="https://physics.stackexchange.com/questions/37571/formulas-for-compressibility-of-solids">Formulas for compressibility of solids</a> </p>
</blockquote>
<p>I have a question which is technically a physics question, but since I have yet t... | https://physics.stackexchange.com/questions/38246/formulas-for-compressibility-of-solids-physics |
Question: <p>i mean given a system with a conserved Energy in one dimension</p>
<p>$$ E= \frac{p^{2}}{2m}+V(x) $$</p>
<p>then the 'solution' to this problem is implicitly given by</p>
<p>$$ t(x)= \frac{1}{2m} \int_{0}^{x}\frac{du}{\sqrt{E-V(u)}} $$</p>
<p>so apparently from this equation we could know all the quant... | https://physics.stackexchange.com/questions/51774/all-the-1-dimensional-problems-in-newtonian-mechanics-are-solvable |
Question: <p>How do you find the net <a href="http://en.wikipedia.org/wiki/Mechanical_advantage" rel="nofollow">Mechanical Advantage</a> (MA) of two joint machines. Do you add or multiply the individual MA?</p>
<p>Suppose I have two sets of wheel and axle connected by a fixed pulley. Each of the wheel has a radius of ... | https://physics.stackexchange.com/questions/51615/total-mechanical-advantage |
Question: <p>I often see the term "net mechanical efficiency" used in literature, but I am not quite sure what it means, and what the difference is between it and "normal" efficiency. Take this sentence for example: <code>... increased the effectiveness, while reducing net mechanical efficiency.</code> What does exactl... | https://physics.stackexchange.com/questions/52697/what-does-net-mechanical-efficiency-mean |
Question: <p>I bought the Lego Kit LEGO Crazy Contraptions. It allows the learner to build a blender. My son, the engineer, said something to our grandson, his son, about a gear ratio. Can someone translate?</p>
Answer: <p>A blender spins very fast, presumably faster than the motor supplied in that kit. A gear is ... | https://physics.stackexchange.com/questions/56557/lego-blender-and-gear-ratios |
Question: <p>My text use the following example to explain the center of mass. There are three balls (mass $m$) sitting in the origin, at $x=l$ and $x=2l$, each two mass are connected with a spring of constant $k$. The system can only move along $x$ direction. To find the center of mass, I setup the coordinate system wi... | https://physics.stackexchange.com/questions/60963/whats-the-center-of-mass-for-triatomic-molecule-system |
Question: <p>if a simple pendulum is dropped in a elevator with a acceleration greater than acceleration due to gravity then what will be its frequency ? We know time period depends on frequency.</p>
Answer: <p>Same formula as usual but with the difference that. $$ g\rightarrow g\pm g'$$ where $g'$ is the acceleratio... | https://physics.stackexchange.com/questions/65107/if-a-simple-pendulum-is-dropped-in-a-elevator-with-a-acceleration-greater-than-a |
Question: <p>Given a certain running pace uphill, I want to be able to determine an equivalent pace running with no elevation change. Assumptions: similar effort in both cases (say for example running at 90% max heart rate), ignore wind, slope is constant for simplicity, ignore physiological and bio-mechanical factors,... | https://physics.stackexchange.com/questions/5882/convert-running-speed-uphill-to-equivilent-speed-on-flat |
Question: <p>In a Feynman book, he talks about a man (I believe he lived 400-500 years ago) that discovered something about the dimensions of triangles (I think)by hanging a chain around the triangle. I've searched in "Six Not So Easy Pieces" but haven't been able to find it.</p>
<p>I'm trying to find the name of thi... | https://physics.stackexchange.com/questions/12792/name-of-the-guy-that-feynman-mentioned-during-a-lecture-the-diagram-is-of-a-cha |
Question: <p>The kinetic energy of a particle is a periodic function in time. Does it imply that the particle is in a conservative force field and there are no dissipative forces acting on it at any instance of time ?</p>
<p><strong>EDIT</strong> (in view of comment by Willie)</p>
<p>Please consider the question as "... | https://physics.stackexchange.com/questions/13878/kinetic-energy-and-conservative-force-field |
Question: <p>Consider an imaginary vertical plane. Now say, a body is falling freely (under earth's attraction). If you consider any axis that is perpendicular to that plane. We get a non-zero value for torque. Then why is it that body is not moving in a circular path about that axis?</p>
Answer: <p>When you exert a t... | https://physics.stackexchange.com/questions/14080/confusion-with-the-torque |
Question: <p>This is a question I originally <a href="https://math.stackexchange.com/questions/70746/what-does-this-infinitesimal-eulerian-change-describe">posted</a> in math.se which received an answer that was far too mathematically sophisticated for what I wanted; given that basic multivariable calculus was used thr... | https://physics.stackexchange.com/questions/16279/what-does-this-infinitesimal-eulerian-change-describe |
Question: <p>I have tried verifying the numerical integration of the Coriolis effect for 1000 to 2000-yard rifle fire by switching ON/OFF the Coriolis correction of a good ballistic simulator program (PRODAS). The program integrates an instantaneously evaluated Coriolis acceleration along with the aerodynamic and gravi... | https://physics.stackexchange.com/questions/17342/how-should-a-closed-ended-terrestrial-trajectory-be-corrected-for-the-coriolis-e |
Question: <p>Say I have a linear motor [aka rail-gun] and use a x amount of electrical power. I fire the gun and the object exits at velocity v. I then reuse the same object as my projectile and fire the rail-gun a second time this time with 2x the electrical power. My lessons on momentum suggest it will go 2v. The... | https://physics.stackexchange.com/questions/19395/how-fast-will-the-projectile-go-the-second-time |
Question: <blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="https://physics.stackexchange.com/questions/19552/would-a-light-or-a-heavy-ball-roll-fastest-down-a-slope">Would a light or a heavy ball roll fastest down a slope?</a> </p>
</blockquote>
<p>Is there a change of the accelleration of an o... | https://physics.stackexchange.com/questions/19548/does-mass-affects-accelleration-of-an-object-in-a-sloapy-movement |
Question: <p>I have a one BHP water pump, the water pressure of a coiled hose connected to the water pump output side was not that great. Would an unwound water hose produce greater water pressure? [Friction Losses?]</p>
<p>Thanks,
Alan</p>
Answer: <p>Yes, but under normal circumstances (e.g. garden hose scale) you w... | https://physics.stackexchange.com/questions/20656/does-a-straight-water-hose-issue-water-at-a-greater-pressure-than-a-coiled-water |
Question: <p>Suppose I can compute interaction energy of two rigid bodies as a function of their coordinates of centers of masses and Euler rotation angles (total 6 + 6 degrees of freedom). Now I can numerically compute force acting on the center of mass of the body by calculating numerical derivatives e.g. $F_x = (E(x... | https://physics.stackexchange.com/questions/29022/numerical-torque-calculation |
Question: <p>While studying uniform circular motion at school, one of my friends asked a question:</p>
<p>"How do I prove that the path traced out by a particle such that an applied force of constant magnitude acts on it perpendicular to its velocity is a circle?" Our physics teacher said it was not exactly a very si... | https://physics.stackexchange.com/questions/30614/path-traced-out-by-a-point |
Question: <p>I am a bit confused about what seems like it should be a perfectly straightforward problem in mechanics with a well defined solution.</p>
<p>A sphere approaches a wall from an angle and rebounds elastically. The coefficient of static friction between sphere and wall is large—no slipping occurs during the ... | https://physics.stackexchange.com/questions/440212/ball-bouncing-elastically-off-a-wall-with-no-slipping |
Question: <p>I'm studying dynamics by Anil Rao's book. He said something that made me really confused. The citations below construct the problem.</p>
<blockquote>
<p>[...]</p>
<p>An assumption of Newtonian mechanics is that space is invariant with
respect to changes in reference frames, i.e., observations made of
space... | https://physics.stackexchange.com/questions/451280/invariance-of-space-and-time-in-different-reference-frames |
Question: <p>When studying the kinematic motion of a rigid body, angular velocity <span class="math-container">$\omega$</span> is a vector that not seem to specify a unique axis of rotation... When looking at the free rigid body motion of a wheel rolling without sliding, we can talk about the wheel's rotation from the... | https://physics.stackexchange.com/questions/452360/does-the-axis-of-rotation-of-a-rigid-body-depend-on-the-frame-of-reference |
Question: <p>If there is a satellite in orbit in space, with an off centre booster providing an unbalanced force, it will experience rotational acceleration. However, I was wondering if it also undergoes linear acceleration while spinning, or only for a brief moment at the start...</p>
Answer: <p><img src="https://i.s... | https://physics.stackexchange.com/questions/510025/linear-acceleration-on-a-spinning-satellite-with-an-unbalanced-force |
Question: <p>Let's say we have a drop of water on a surface. Its surface tension maintains the shape. But was the water evaporates, the molecules leaving it, leave from the surface. Shouldn't the evaporation disturb the surface tension causing the water droplet to fall apart?</p>
Answer: <p>As the drop gets smaller... | https://physics.stackexchange.com/questions/534574/how-does-a-drop-of-water-evaporate-and-still-maintain-its-drop-shape |
Question: <p>The classic introductory mechanics problem considers the motion of a box sliding down an inclined plane. As I'm reviewing the early chapters in Taylor's <em>Classical Mechanics</em>, I was struck by a question: in such a problem, we always <em>say</em> that the box has no motion in the y-direction (as is s... | https://physics.stackexchange.com/questions/546228/box-sliding-down-an-inclined-plane-underlying-assumption |
Question: <p>So we have a train going 5 m/s that gets loaded with 20,000 kg of coal while going over a 10m platform for 2 s. There is a 50,000 N horizontal force applied to the train during that period in order to keep the train going a constant 5 m/s.</p>
<p>That 50,000 N force does 500,000 J of work. But the KE of th... | https://physics.stackexchange.com/questions/581827/conservation-of-energy-question-train-example |
Question: <p>I'm a math student who's studying classical mechanics for the first time, so forgive me if this question sounds pedantic, but I find it hard to think about such problems without stating assumptions clearly.</p>
<p>If a frame K' is accelerating away from an inertial frame K, we wish to transform from the in... | https://physics.stackexchange.com/questions/658470/coordinate-transformation-to-non-inertial-frame-do-we-assume-displacement-is-in |
Question: <p>When a particle elastically collides with a hard wall at some velocity, can the point at which the particle instantenously jumps be assumed to have zero velocity for potential to be continuous?</p>
Answer: <p>Assuming a head-on collision (or only considering the normal component of the velocity), we could... | https://physics.stackexchange.com/questions/716422/particle-collides-with-hard-wall |
Question: <p>Does there exist a particular physical system where the initial velocity can be zero, but non-zero constant everywhere else?</p>
Answer: <p>If the velocity is constant the force is zero. So we want a system which produces a very high force in an infinitesimally short time at <span class="math-container">$... | https://physics.stackexchange.com/questions/716442/can-a-physical-system-have-initial-velocity-zero-but-non-zero-constant-everywhe |
Question: <p>Isn’t <span class="math-container">$\sqrt{c^2 - v^2/c^2} $</span> the mathematical equivalent of
<span class="math-container">$\sqrt{1 - v^2/c^2}$</span>? Why do we never see it presented this way?</p>
Answer: <p>Are you asking why we never see <span class="math-container">$\sqrt{\frac{c^2-v^2}{c^2}}$</... | https://physics.stackexchange.com/questions/730910/isn-t-c2-v2-c21-2-the-mathematical-equivalent-of-1-v2-c21 |
Question: <p>An question I am doing gives this situation:
<img src="https://i.sstatic.net/EMo57.jpg" alt="enter image description here"></p>
<p>Mass1 is 4kg. And mass2 is 7kg. </p>
<p>I expect the tension to be the same, no matter which mass I use in the calculation. But...</p>
<p>a=5.17</p>
<p>T1=7(9.81-5.17)=32.4... | https://physics.stackexchange.com/questions/213262/why-may-tensions-calculated-in-different-ways-be-slightly-different |
Question: <p>I was wondering why friction vectors are drawn differently regarding a cylinder rolling on a surface and a cylinder rolling down an inclined surface. Since friction is responsible for the rotational motion shouldn't it be always pointing in the same direction (given that the cylinder is rotating to the rig... | https://physics.stackexchange.com/questions/214643/friction-of-a-rolling-cylinder |
Question: <p>This might be a very simple question. I read one previous post
<a href="https://physics.stackexchange.com/questions/231185/can-the-kinetic-energy-be-a-function-of-the-position-vector">Can the kinetic energy be a function of the position vector?</a></p>
<p>I know that in Cartesian coordinates, the kinetic... | https://physics.stackexchange.com/questions/233073/again-why-is-kinetic-energy-and-velocity-independent-of-position-coordinates-in |
Question: <p>I have a car, that has a current angle and location, and a destination angle and location. The car has a maximum linear and angular acceleration. Assume the car will always travel in the direction it is facing. I'm trying to figure out how to determine the path that this car should travel that will be the ... | https://physics.stackexchange.com/questions/240156/moving-a-car-the-quickest-path |
Question: <p>Please refer to the figure attached. Consider a normal force is acting on the top of sphere. A constant coefficient of friction causes frictional force throughout the sliding. I want to know after this sphere slides (pure sliding no rolling) for sometime and assuming that it wears as it slides, what should... | https://physics.stackexchange.com/questions/267665/sliding-sphere-wear-shape |
Question: <p>It is a shiny object in broad daylight, the distance seems quite far away, is there sufficient information in the footage to ascertain if it is a meteorite captured on film or something else?</p>
<p><a href="https://i.sstatic.net/PC3gE.gif" rel="nofollow noreferrer"><img src="https://i.sstatic.net/PC3gE.... | https://physics.stackexchange.com/questions/304770/is-this-a-metorite-captured-on-film-or-a-bird-plane-etc |
Question: <p>If we have two reference systems, <span class="math-container">$N$</span> and <span class="math-container">$B$</span>, with common origins <span class="math-container">$O_N=O_B$</span> and <span class="math-container">$B$</span> being rotating around <span class="math-container">$N$</span> with angular vel... | https://physics.stackexchange.com/questions/399424/transport-theorem-in-analytical-dynamics-basis-of-the-vectors |
Question: <p>In the textbooks of classical mechanics I have been through, it is often quoted that, given an <span class="math-container">$N$</span> particle system having <span class="math-container">$3N$</span> Cartesian coordinates <span class="math-container">$(x_i,y_i,z_i)$</span> connected by <span class="math-con... | https://physics.stackexchange.com/questions/601508/how-does-the-actual-elimination-of-dependent-coordinates-takes-place |
Question: <p>I'm not sure I understand this topic so I would be happy if someone could clarify it for me:</p>
<p>Is precession (say, of a spinning top) generally speaking a change in the <strong>direction</strong> of the angular velocity vector over time? Is that why it is sometimes said that whenever <span class="math... | https://physics.stackexchange.com/questions/602576/the-angular-momentum-and-angular-velocity-roles-in-precession |
Question: <p>Because the force applied on a body obviously would act on a particular area, and not the whole body.</p>
Answer: <p>Because it's a lot easier to work with. You could use pressure to calculate how an object will move/behave but you would have to work out the average pressure acting on the body and multipl... | https://physics.stackexchange.com/questions/603949/why-dont-we-consider-pressure-as-the-driving-agency-for-motion-instead-of-forc |
Question: <p>I have a ball attached to a spring and the spring is attached to a wall. There is no gravity for simplicity. In the rest RF the oscillating ball energy is conserved: T + U = const. In a moving RF it is not conserved. I would like to see the shortest answer to the question "Why?".</p>
<p>| <--... | https://physics.stackexchange.com/questions/4827/is-the-total-energy-conserved-in-a-moving-reference-frame |
Question: <p>In the paper, <a href="https://www.researchgate.net/publication/228609262_Development_of_an_Aerodynamic_Model_and_Control_Law_Design_for_a_High_Altitude_Airship_presented_at" rel="nofollow noreferrer">Development of an Aerodynamic Model and Control Law Design for a High Altitude Airship</a> I found a passa... | https://physics.stackexchange.com/questions/583498/why-does-the-net-lift-of-an-airship-remain-constant-when-the-kg-of-air-it-displa |
Question: <p>Torque = r x F = r*F*sin(theta) => So units will be kg*m^2/s^2</p>
<p>Torque = I*alpha => SI units is kg*m^2*rad/s^2</p>
<p>There is a rad unit extra in the second formula. They both should match right because they are calculating torque.</p>
Answer: <p>Rad or radians has no physical dimensions and ... | https://physics.stackexchange.com/questions/587464/matching-torque-si-units-from-two-different-formula |
Question: <p>When an object is thrown upwards, when it eventually comes to rest and starts falling, for how long is it stationary? What about an particle in electric field having an initial velocity towards it's same charge? That too would come to rest and reverse velocity, the question is for how long is it at full st... | https://physics.stackexchange.com/questions/3372/non-classical-mechanic-answer-to-length-of-time-a-thrown-object-spends-in-rest |
Question: <p>So I think my algebra is wrong somewhere.
Lets say you have an object that goes under SHM with some initial conditions (amplitude is 5m. The piston is at 5m at t = 0 and period is 20 seconds).</p>
<p>Okay so $x(t) = A sin(\omega_0 + \phi)$. $\phi$ for us is 0. The frequency = $0.05 Hz$, angular frequency ... | https://physics.stackexchange.com/questions/4189/max-velocity-of-shm |
Question: <p>I'm trying to calculate the magnitude and direction of the force exerted on a wheel when encountering a step. The wheel and the steps are non-deformable.</p>
<p>I found two different approaches:</p>
<ul>
<li><p>energy approach, from which I can calculate the difference in speeds before and after, but I hav... | https://physics.stackexchange.com/questions/574523/force-on-suspension-when-hitting-a-step |
Question: <p>In Rigid body rotation, we need only 3 parameters to make a body rotate in any orientation. So to define a rotation matrix in 3d space we only need 3 parameters and we must have 6 constraint equation (6+3=9 no of elements in rotation matrix)</p>
<p>My doubt is if orthogonality conditions R.Transpose(R)=I m... | https://physics.stackexchange.com/questions/575225/constaints-in-rotation-matrix |
Question: <p>Say there a child, that stands on the edge of an AT REST merry go round. When they jump off, the child has a linear velocity, and the merry go round begins to turns.</p>
<p>They say there is no net torque on the merry go round/child system and angular momentum is conserved.</p>
<p>I understand the torque a... | https://physics.stackexchange.com/questions/577125/torque-when-jumping-from-at-rest-merry-go-round-conservation-of-angular-momentu |
Question: <p>I'm running into some confusion understanding rotations as being instantaneous cross products of angular velocity vectors. I would like to highlight two approaches which seem like they contradict each other, in the hopes that somebody can explain the conceptual error being made.</p>
<p><strong>Approach 1</... | https://physics.stackexchange.com/questions/585208/angular-velocity-and-rotation-matrices |
Question: <p>I am ignorant of physics besides college, and I would like to know if it is possible that a moon rotates its mother planet for an infinite time assuming there is no resistance of any form.</p>
<p>I came up with this question since once a moon starts rotating, it keeps rotating according to law of gravity. ... | https://physics.stackexchange.com/questions/593615/is-it-possible-that-a-satellite-rotates-planet-infinitely-without-air-resistance |
Question: <p>The 'total energy' of a particle in an isolated system is conserved only if all the forces on it are conservative. For a conservative force, we need a force dependent only on the current position of the particle, right? Is every force in the universe like that? Coloumb and Gravitation Forces are like that,... | https://physics.stackexchange.com/questions/535953/are-all-kinds-on-forces-between-particles-only-dependent-on-the-distance-between |
Question: <p>Consider a heavy particle moves inside a frictionless hollow sphere with radius a.<br>
The particle is
held on the inner surface of the sphere at z = −a/2, where z is measured upwards from the centre of the sphere. Given a horizontal velocity U. If U squared = 4ag,
find the maximum and minimum height that... | https://physics.stackexchange.com/questions/536095/what-happens-if-a-particle-moving-in-a-hollow-sphere-is-given-a-horizontal-veloc |
Question: <p>We affirm that free falling bodies are by definition bodies that are subject to the sole force of gravity. We state that free falling bodies fall through equal distances in equal times regardless their different weight. Most of the experiments that show this evidence are executed in normal conditions here ... | https://physics.stackexchange.com/questions/536270/free-falling-bodies-why-air-resistance-is-not-considered |
Question: <p>What is the physics of shooting a moving target from a moving target? Bullet turns, target moves, and one have to pre-aim to compensate the difference such as World War II fighter plane. Does it even have a name?</p>
Answer: <p>Shooting at a moving target, whether or not you are moving, is known as deflec... | https://physics.stackexchange.com/questions/536716/shooting-a-moving-target-from-a-moving-target |
Question: <p>I'm getting different definitions from different sources. Some claim that free particles have no forces acting on them at all (i.e. even if a particle has forces acting on it such that they cancel, it's not free). Other sources explicitly state that there is no net force (like <a href="https://www.tau.ac.i... | https://physics.stackexchange.com/questions/537933/is-a-free-particle-one-on-which-theres-no-net-force-or-one-on-which-theres-no |
Question: <p>In problem 3 of chapter 2 of Landau Lifshitz "Mechanics," I don't understand the meaning of the fields as defined in the following statement:</p>
<blockquote>
<p>Which components of momentum and angular momentum are conserved in motion in the following fields?</p>
<p>(a) the field of an infinite ... | https://physics.stackexchange.com/questions/41925/what-are-the-fields-in-this-problem |
Question: <p>Imagine a situation where a long masless stick is inserted through a ring, and fix one of the ends of the stick. Then, the system is given an impulsive force such that it starts rotating with an initial velocity <span class="math-container">$\omega_0$</span>, the ring will start moving outwards, and thus, ... | https://physics.stackexchange.com/questions/565672/spiral-path-of-particle-moving-under-circular-force |
Question: <p>Let's assume a mass that is hanging somewhere. My question is basically:</p>
<ol>
<li>We are applying a force from the side to move the mass sidewards</li>
<li>We are applying a force from below to move the mass upwards</li>
</ol>
<p>Are these forces the same?</p>
<p>In this context, a bit more concise and... | https://physics.stackexchange.com/questions/565901/are-forces-from-different-directions-applied-to-a-hanging-mass-the-same |
Question: <p>On page <span class="math-container">$41$</span> Landau states that the total momentum in the C system is <span class="math-container">$0$</span>.</p>
<p>On page <span class="math-container">$43$</span> for the disintegration of many particles, Landau states: In the C system... every resulting particle (of... | https://physics.stackexchange.com/questions/571565/disintegration-of-many-particles-landau-mechanics-3rd-ed-page-43 |
Question: <p>I have a question from an example we done in lecture</p>
<p>Suppose we have a particle moving inside the surface of a cone given by $r = wz$ where $w$ is a constant,</p>
<p>and also suppose initially the particle is moving horizontally at height $b$ and speed $U$,the lecturer then stated these "facts"</p... | https://physics.stackexchange.com/questions/104836/horizontal-motion-inside-a-cone-cylindrical-polars |
Question: <p>Imagine a particle tracing a counter-clockwise circular path on a flat table with a certain speed. The particle is tied with a massless string of length $R$ to a point $P$ at the center of the circular path. Will the particle rotate about $P$ forever at constant speed in the absence of any external force? ... | https://physics.stackexchange.com/questions/109211/how-to-reconcile-angular-momentum-measurements |
Question: <p><strong>Setup</strong></p>
<p>Imagine a two-body system of masses under a classical mechanics model. The separation and mass-ratio doesn't matter for this example. Presume they are initially stationary.</p>
<p>Now suppose that we hold one of the masses, m1, permanently stationary with an external force o... | https://physics.stackexchange.com/questions/109239/two-body-with-external-force-energy-confusion |
Question: <p>Has anyone done any research about the upwind vehicle <a href="http://www.popsci.com/cars/article/2012-07/wind-powered-car-travels-upwind-twice-speed-wind" rel="nofollow">http://www.popsci.com/cars/article/2012-07/wind-powered-car-travels-upwind-twice-speed-wind</a>?</p>
<p>I think it is impossible but ge... | https://physics.stackexchange.com/questions/110395/upwind-vehicle-exceeding-the-wind-speed |
Question: <p>From my point of view, it seems that a soldier armed with a <strong>full metal plate armor</strong> was almost invulnerable at the time their opponents yielded swords, spears or bows. I understand that it couldn't be the case, but I'm not sure about the physics behind it.</p>
<p>More specifically:</p>
<o... | https://physics.stackexchange.com/questions/113124/how-was-it-possible-to-beat-a-soldier-with-a-full-plate-armor |
Question: <p>Simple question - Does lever needs gravitation force to work or it just needs fulcrum and could work in vacuum as well?</p>
Answer: <p>A lever can work in zero-gravity conditions as long as the fulcrum and lever arm are physically attached. They also work regardless of atmospheric presence.</p>
| https://physics.stackexchange.com/questions/131044/does-lever-needs-gravitation-to-work |
Question: <p>Given a car that has two lines of wheels, the center of gravity at constant height above the ground, constant turn angle and given surface and wheel material.</p>
<p>What is the maximum speed the car can drive without the wheels sliding given the position of center of gravity (leaning in, leaning out or c... | https://physics.stackexchange.com/questions/132476/which-way-to-lean-when-driving-a-gokart |
Question: <p>Where can I find maps of physical concepts illustrating the connection & logical relations between concepts . I think it can be of a great help to summarize what I learnt . </p>
Answer: | https://physics.stackexchange.com/questions/134046/concept-map-graph |
Question: <p>TL;DR Given the point of centre of mass, width of base and height, is there a way to calculate the angle where the object will fall over?</p>
<p>The TL;DR of this question pretty much sums it up, however I wanted to give an example.</p>
<p>Let us say that we have a cuboid made of uniform weight wood with... | https://physics.stackexchange.com/questions/150582/how-to-calculate-when-an-object-will-fall-over |
Question: <p>No doubt a very simple question with an easy answer that's been puzzling me:</p>
<p>If I'm riding my bicycle in the $x$ direction with speed $v$ and turn my handlebars I can end up travelling in the $y$ direction with almost the same speed without having to provide any additional energy. I don't have to c... | https://physics.stackexchange.com/questions/156197/how-do-i-turn-my-bicycle |
Question: <p>If you have a system of forces and you take moments about two different points will the moment be the same?</p>
Answer: <p>No. You can see now why dealing with torques and angular momentum is so difficult: It depends on what point in space you are taking it with respect to. The torque about one point may ... | https://physics.stackexchange.com/questions/165074/taking-moments-about-two-different-points-in-a-system-of-forces |
Question: <p>Supposed we have someone on a moving platform which is at constant velocity. Lets say the person launches a mass at some speed relative to the platform an some angle with respect to the platform. Does the launch angle differs from say someone on the ground? </p>
<p>I know velocities are relatives, but I r... | https://physics.stackexchange.com/questions/171988/are-launch-angles-relative-to-observers |
Question: <p>As I see it, the definition of kinetic energy
$$T= {1\over2} m u^2 \text { where $u<<c$}$$
comes by using the definition of work
$$W= {\int F\cdot\ dx }$$
and we use for the meaning of F(force) the Second Law of Newton:
$$F={dp\over dt}=ma$$</p>
<p>Do I understand correctly that the kinetic ener... | https://physics.stackexchange.com/questions/176436/definition-of-kinetic-energy-without-the-second-law-of-newton |
Question: <p><a href="https://www.youtube.com/watch?v=SRGf0Mq2Zwg" rel="nofollow">https://www.youtube.com/watch?v=SRGf0Mq2Zwg</a></p>
<p>I want to read the physical and mathematical model of this "bouncing balls separator " in the above link .</p>
<p>What is name of this experiment so I can search it in literature ?<... | https://physics.stackexchange.com/questions/184308/name-of-this-bouncing-balls-separator-model |
Question: <p>Balloons are definitely not gas-tight. Carbon dioxide just leak by the rubber away. A balloon is filled with carbon dioxide. Knot in it. And play. Shrinkage. After an hour or two the carbon dioxide balloon has dramatically shrunk in size. Apparently carbon dioxide creeps much faster through the rubber bal... | https://physics.stackexchange.com/questions/187868/what-are-possible-explanations-for-the-permeability-of-balloon-rubber-pet-plast |
Question: <p>Why is it that $v\cdot sin(x)$ gives the vertical component and $v \cdot cos(x)$ gives the horizontal component, where $v$ is the speed? What logic is there behind it, or even better is there a proof to back it up?</p>
<p>I know by drawing a right angled triangle you can find out the components, but I wan... | https://physics.stackexchange.com/questions/191201/proof-of-vertical-and-horizontal-velocity-component-in-projectile-motion |
Question: <p>If I take a rod and bend it at both ends as far as it will go, why is there an assumption that I am also exerting a torsion along with my bending?</p>
<p>Referencee: ccording to the third edition of "Theory of Elasticity": </p>
<blockquote>
<p>"It is important to note that, when a rod undergoes larding... | https://physics.stackexchange.com/questions/188334/why-is-a-bending-rod-assumed-to-be-undergoing-torsion |
Question: <p>So I have recently started looking into moments of inertia, and all that stuff. I have come to a question which has a plane inclined at some angle theta and a sphere at the peak. The G.P.E at the top is mgh. The plane is frictionless.The book then states by conservation of energy $mgh = 1/2(mv^2) + \text{r... | https://physics.stackexchange.com/questions/196946/how-does-rotational-energy-transfer-to-linear-energy |
Question: <p>Consider the motion of a coffee cup in the gravitation field of earth. The force acting on the cup apparently depends on the orientation of the cup. Therefore, the internal rotation (with respect to its center of mass) of the cup is coupled with its center-of-mass motion. Is this a classical counterpart of... | https://physics.stackexchange.com/questions/200574/spin-orbit-coupling-for-a-rigid-body |
Question: <p>If you place a metal block in a tub of small frictionless ball bearings of the same metal, would it stay on top or sink?..</p>
Answer: <p>The block will have higher density because of the air gaps between the steel balls so it should sink to the bottom.</p>
| https://physics.stackexchange.com/questions/197187/a-metal-block-in-a-tub-of-frictionless-ball-bearings |
Question: <p>In the following video can someone explain why did he take the limits of integration to be from $-\frac{\pi}{2}$ to $\frac{\pi}{2}$ ?
<a href="https://www.youtube.com/watch?v=bJWFgJTxIFk&index=9&list=PLYVDsiuOZP5pNzoB-e4ugTz96dGpspdDI" rel="nofollow">https://www.youtube.com/watch?v=bJWFgJTxIFk&... | https://physics.stackexchange.com/questions/200830/limits-of-integration |
Question: <p>Must the shape functions and the interpolation functions (which are the same in an isoparametric element) in a finite element model be elements of a Hausdorff space? If so, is this necessary to ensure convergence to a unique solution when the mesh is refined? If not, what are the requirements for these... | https://physics.stackexchange.com/questions/202505/hausdorff-spaces-and-finite-elements |
Question: <p>I read somewhere that an inertial navigation system, in order to be accurate, must take the Coriolis effect into account. Why is this so? If I go a 500 mph velocity in a given direction, I'm going 500 mph, so in 1 hour, I should be 500 miles from the airport whether I'm traveling N, E, or W. </p>
Answer: ... | https://physics.stackexchange.com/questions/205126/why-must-an-inertial-navigation-system-take-the-coriolis-effect-into-account |
Question: <p>Studying vector calculus you learn to prove that a particle moving in a gravitational field will, in that field respect that $dU=-dW$. From this you can conclude $U_2+K_2=U_1+K_1$. </p>
<p>This is easy to prove in here but I fail to see how to prove it for, suppose, $n$ charged particles or massive partic... | https://physics.stackexchange.com/questions/205145/a-system-of-particles-interacting-via-conservative-forces-will-also-respect-u |
Question: <p>I know when cars drive, there is action and reaction pair on the wheel, then is it possible to speed up or slow down the rotation of Earth if all cars and other machines travel towards one direction together?</p>
Answer: <p>Earth + machines is an isolated system so angular momentum is conserved
\begin{ali... | https://physics.stackexchange.com/questions/207444/can-we-change-the-rotation-speed-of-earth-if-all-cars-planes-ships-etc-travel |
Question: <p>A person holds the handle of a folding knife in their hand with the pivot point of the blade between their index finger and thumb. The blade points away from the body and the other fingers grip the handle in a way not to impede the opening of the blade. The friction at the pivot point is just enough for th... | https://physics.stackexchange.com/questions/212150/how-physics-opens-a-knife-with-a-flick-of-the-wrist |
Question: <p>This question comes into my mind this evening. </p>
<p>Suppose I have a rotating disc whose maximum rotation speed is $500$ rpm (say). On this rotating disc I have placed another small rotating disc with same property and in such a way that both can rotate in this configuration. Now if I started the disc ... | https://physics.stackexchange.com/questions/218166/rotating-disc-problem |
Question: <p>Is it a valid question to ask what is the percentage of light that gets refracted by H 2 for a certain distance(Lets say 1 light year) in deep space. Lets assume a few(3) Hydrogen atoms per cubic meter. </p>
Answer: | https://physics.stackexchange.com/questions/228538/probability-of-light-being-refracted-in-deep-space-by-h-2hydrogen |
Question: <p>Does the object's normal force and $mg$ cancel out, resulting in the two force becoming equal, or would one force be greater than the other? Thank you!
Edit: Also would the $mg$ be considered weight or would it be more correct to just refer to the force as $mg$? </p>
Answer: <p>If the object is moving on ... | https://physics.stackexchange.com/questions/228701/when-an-object-is-moving-at-a-constant-velocity-would-the-normal-force-and-mg |
Question: <p>If a wheel is detached from a moving vehicle, would it speed be higher than the vehicle? Why?</p>
Answer: <p>Assume the car travels at speed $v$ and the wheel has a radius $R$. Assume also that the wheel was rolling without slipping, then:</p>
<p>$$v=\omega R,$$</p>
<p>where $\omega$ is the <em>angular ... | https://physics.stackexchange.com/questions/228301/detached-wheel-from-a-moving-vehicle-speed |
Question: <p>When I'm standing in a train car and the train starts slowing down relatively quickly, I instinctively flex certain muscles in my legs and that helps me keep my footing. </p>
<p>What muscles am I flexing and how does flexing them help me maintain my balance and avoid falling?</p>
Answer: <p>I'll answer t... | https://physics.stackexchange.com/questions/226483/how-am-i-able-to-keep-my-footing-on-an-accelerating-platform |
Question: <p>In the explanation of the nature of gases we use the kinetic formula $PV=1/3(mnc)$
where $p$ is pressure, $v$ volume, $m$ mass, $n$ number of molecules and $c$ means root mean square velocity. But in its explanation I don't understand why everyone uses time to measure the change of momentum of a particular... | https://physics.stackexchange.com/questions/231889/kinetics-of-gas-molecule |
Question: <p>I was doing a question on energy and forces, and it goes as follows:(Doesn't require knowledge of calculus):</p>
<blockquote>
<p>If a bullet with velocity $v$ penetrates a bag upto a distance $x$,
then find the distance which bullet penetrates if velocity becomes
$2v$.</p>
</blockquote>
<p>I tried ... | https://physics.stackexchange.com/questions/232326/if-a-bullet-penetrates-a-bag-how-come-the-repulsive-force-is-constant |
Question: <p>Can a point mass have vibrational motion. I have read that reason for point mass is to ensure that we can idealize translational motion and don't have to worry about rotational and vibrational motion. Is that correct?</p>
Answer: <p>It depends what you mean by vibrational motion. A point mass indeed does ... | https://physics.stackexchange.com/questions/234561/can-point-mass-have-vibrational-motion |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.