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magnitude of kinetic friction : fk=μkNfk=μkN, whereμkμkis the coefficient of kinetic friction
https://openstax.org/books/college-physics-2e/pages/5-glossary
magnitude of static friction : fs≤μsNfs≤μsN, whereμsμsis the coefficient of static friction andNNis the magnitude of the normal force
https://openstax.org/books/college-physics-2e/pages/5-glossary
shear deformation : deformation perpendicular to the original length of an object
https://openstax.org/books/college-physics-2e/pages/5-glossary
static friction : a force that opposes the motion of two systems that are in contact and are not moving relative to one another
https://openstax.org/books/college-physics-2e/pages/5-glossary
Stokes’ law : Fs=6πrηvFs=6πrηv, whererris the radius of the object,ηηis the viscosity of the fluid, andvvis the object’s velocity
https://openstax.org/books/college-physics-2e/pages/5-glossary
strain : ratio of change in length to original length
https://openstax.org/books/college-physics-2e/pages/5-glossary
stress : ratio of force to area
https://openstax.org/books/college-physics-2e/pages/5-glossary
tensile strength : the breaking stress that will cause permanent deformation or fraction of a material
https://openstax.org/books/college-physics-2e/pages/5-glossary
Friction is a contact force between systems that opposes the motion or attempted motion between them. Simple friction is proportional to the normal forceNNpushing the systems together. (A normal force is always perpendicular to the contact surface between systems.) Friction depends on both of the materials involved. Th...
https://openstax.org/books/college-physics-2e/pages/5-section-summary
The kinetic friction forcefkfkbetween systems moving relative to one another is given byfk=μkN,fk=μkN,whereμkμkis the coefficient of kinetic friction, which also depends on both materials.
https://openstax.org/books/college-physics-2e/pages/5-section-summary
Drag forces acting on an object moving in a fluid oppose the motion. For larger objects (such as a baseball) moving at a velocityvvin air, the drag force is given byFD=12CρAv2,FD=12CρAv2,whereCCis the drag coefficient (typical values are given inTable 5.2),AAis the area of the object facing the fluid, andρρis the f...
https://openstax.org/books/college-physics-2e/pages/5-section-summary
For small objects (such as a bacterium) moving in a denser medium (such as water), the drag force is given by Stokes’ law,Fs=6πηrv,Fs=6πηrv,whererris the radius of the object,ηηis the fluid viscosity, andvvis the object’s velocity.
https://openstax.org/books/college-physics-2e/pages/5-section-summary
Hooke’s law is given byF=kΔL,F=kΔL,whereΔLΔLis the amount of deformation (the change in length),FFis the applied force, andkkis a proportionality constant that depends on the shape and composition of the object and the direction of the force. The relationship between the deformation and the applied force can also...
https://openstax.org/books/college-physics-2e/pages/5-section-summary
whereΔLΔLis the amount of deformation (the change in length),FFis the applied force, andkkis a proportionality constant that depends on the shape and composition of the object and the direction of the force. The relationship between the deformation and the applied force can also be written as
https://openstax.org/books/college-physics-2e/pages/5-section-summary
whereYYisYoung’s modulus, which depends on the substance,AAis the cross-sectional area, andL0L0is the original length.
https://openstax.org/books/college-physics-2e/pages/5-section-summary
The ratio of force to area,FAFA, is defined asstress, measured in N/m2.
https://openstax.org/books/college-physics-2e/pages/5-section-summary
The ratio of the change in length to length,ΔLL0ΔLL0, is defined asstrain(a unitless quantity). In other words,stress=Y×strain.stress=Y×strain.
https://openstax.org/books/college-physics-2e/pages/5-section-summary
The expression for shear deformation isΔx=1SFAL0,Δx=1SFAL0,whereSSis the shear modulus andFFis the force applied perpendicular toL0L0and parallel to the cross-sectional areaAA.
https://openstax.org/books/college-physics-2e/pages/5-section-summary
whereSSis the shear modulus andFFis the force applied perpendicular toL0L0and parallel to the cross-sectional areaAA.
https://openstax.org/books/college-physics-2e/pages/5-section-summary
The relationship of the change in volume to other physical quantities is given byΔV=1BFAV0,ΔV=1BFAV0,whereBBis the bulk modulus,V0V0is the original volume, andFAFAis the force per unit area applied uniformly inward on all surfaces.
https://openstax.org/books/college-physics-2e/pages/5-section-summary
whereBBis the bulk modulus,V0V0is the original volume, andFAFAis the force per unit area applied uniformly inward on all surfaces.
https://openstax.org/books/college-physics-2e/pages/5-section-summary
angular velocity : ωω, the rate of change of the angle with which an object moves on a circular path
https://openstax.org/books/college-physics-2e/pages/6-glossary
arc length : ΔsΔs, the distance traveled by an object along a circular path
https://openstax.org/books/college-physics-2e/pages/6-glossary
banked curve : the curve in a road that is sloping in a manner that helps a vehicle negotiate the curve
https://openstax.org/books/college-physics-2e/pages/6-glossary
center of mass : the point where the entire mass of an object or of a system of objects can be thought to be concentrated
https://openstax.org/books/college-physics-2e/pages/6-glossary
centrifugal force : a fictitious force that tends to throw an object off when the object is rotating in a non-inertial frame of reference
https://openstax.org/books/college-physics-2e/pages/6-glossary
centripetal acceleration : the acceleration of an object moving in a circle, directed toward the center
https://openstax.org/books/college-physics-2e/pages/6-glossary
centripetal force : any net force causing uniform circular motion
https://openstax.org/books/college-physics-2e/pages/6-glossary
Coriolis force : the fictitious force causing the apparent deflection of moving objects when viewed in a rotating frame of reference
https://openstax.org/books/college-physics-2e/pages/6-glossary
fictitious force : a force having no physical origin
https://openstax.org/books/college-physics-2e/pages/6-glossary
gravitational constant,G : a proportionality factor used in the equation for Newton’s universal law of gravitation; it is a universal constant—that is, it is thought to be the same everywhere in the universe
https://openstax.org/books/college-physics-2e/pages/6-glossary
ideal angle : the angle at which a car can turn safely on a steep curve, which is in proportion to the ideal speed
https://openstax.org/books/college-physics-2e/pages/6-glossary
ideal banking : the sloping of a curve in a road, where the angle of the slope allows the vehicle to negotiate the curve at a certain speed without the aid of friction between the tires and the road; the net external force on the vehicle equals the horizontal centripetal force in the absence of friction
https://openstax.org/books/college-physics-2e/pages/6-glossary
ideal speed : the maximum safe speed at which a vehicle can turn on a curve without the aid of friction between the tire and the road
https://openstax.org/books/college-physics-2e/pages/6-glossary
microgravity : an environment in which the apparent net acceleration of a body is small compared with that produced by Earth at its surface
https://openstax.org/books/college-physics-2e/pages/6-glossary
Newton’s universal law of gravitation : every particle in the universe attracts every other particle with a force along a line joining them; the force is directly proportional to the product of their masses and inversely proportional to the square of the distance between them
https://openstax.org/books/college-physics-2e/pages/6-glossary
non-inertial frame of reference : an accelerated frame of reference
https://openstax.org/books/college-physics-2e/pages/6-glossary
pit : a tiny indentation on the spiral track moulded into the top of the polycarbonate layer of CD
https://openstax.org/books/college-physics-2e/pages/6-glossary
radians : a unit of angle measurement
https://openstax.org/books/college-physics-2e/pages/6-glossary
radius of curvature : radius of a circular path
https://openstax.org/books/college-physics-2e/pages/6-glossary
rotation angle : the ratio of the arc length to the radius of curvature on a circular path:Δθ=ΔsrΔθ=Δsr
https://openstax.org/books/college-physics-2e/pages/6-glossary
ultracentrifuge : a centrifuge optimized for spinning a rotor at very high speeds
https://openstax.org/books/college-physics-2e/pages/6-glossary
uniform circular motion : the motion of an object in a circular path at constant speed
https://openstax.org/books/college-physics-2e/pages/6-glossary
Uniform circular motion is motion in a circle at constant speed. The rotation angleΔθΔθis defined as the ratio of the arc length to the radius of curvature:Δθ=Δsr,Δθ=Δsr,where arc lengthΔsΔsis distance traveled along a circular path andrris the radius of curvature of the circular path. The quantityΔθΔθi...
https://openstax.org/books/college-physics-2e/pages/6-section-summary
where arc lengthΔsΔsis distance traveled along a circular path andrris the radius of curvature of the circular path. The quantityΔθΔθis measured in units of radians (rad), for which
https://openstax.org/books/college-physics-2e/pages/6-section-summary
The conversion between radians and degrees is1rad=57.3º1rad=57.3º.
https://openstax.org/books/college-physics-2e/pages/6-section-summary
Angular velocityωωis the rate of change of an angle,ω=ΔθΔt,ω=ΔθΔt,where a rotationΔθΔθtakes place in a timeΔtΔt. The units of angular velocity are radians per second (rad/s). Linear velocityvvand angular velocityωωare related byv=rωorω=vr.v=rωorω=vr.
https://openstax.org/books/college-physics-2e/pages/6-section-summary
where a rotationΔθΔθtakes place in a timeΔtΔt. The units of angular velocity are radians per second (rad/s). Linear velocityvvand angular velocityωωare related by
https://openstax.org/books/college-physics-2e/pages/6-section-summary
Centripetal accelerationacacis the acceleration experienced while in uniform circular motion. It always points toward the center of rotation. It is perpendicular to the linear velocityvvand has the magnitudeac=v2r;ac=rω2.ac=v2r;ac=rω2.
https://openstax.org/books/college-physics-2e/pages/6-section-summary
The unit of centripetal acceleration ism/s2m/s2.
https://openstax.org/books/college-physics-2e/pages/6-section-summary
Centripetal forceFcFcis any force causing uniform circular motion. It is a “center-seeking” force that always points toward the center of rotation. It is perpendicular to linear velocityvvand has magnitudeFc=mac,Fc=mac,which can also be expressed asFc=mv2rorFc=mrω2,Fc=mv2rorFc=mrω2,
https://openstax.org/books/college-physics-2e/pages/6-section-summary
which can also be expressed as
https://openstax.org/books/college-physics-2e/pages/6-section-summary
Rotating and accelerated frames of reference are non-inertial.
https://openstax.org/books/college-physics-2e/pages/6-section-summary
Fictitious forces, such as the Coriolis force, are needed to explain motion in such frames.
https://openstax.org/books/college-physics-2e/pages/6-section-summary
Newton’s universal law of gravitation: Every particle in the universe attracts every other particle with a force along a line joining them. The force is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. In equation form, this isF=GmMr2,F=GmMr2,...
https://openstax.org/books/college-physics-2e/pages/6-section-summary
where F is the magnitude of the gravitational force.GGis the gravitational constant, given byG=6.674×10–11Nâ‹m2/kg2G=6.674×10–11Nâ‹m2/kg2.
https://openstax.org/books/college-physics-2e/pages/6-section-summary
Newton’s law of gravitation applies universally.
https://openstax.org/books/college-physics-2e/pages/6-section-summary
Kepler’s laws are stated for a small massmmorbiting a larger massMMin near-isolation. Kepler’s laws of planetary motion are then as follows:Kepler’s first lawThe orbit of each planet about the Sun is an ellipse with the Sun at one focus.Kepler’s second lawEach planet moves so that an imaginary line drawn from t...
https://openstax.org/books/college-physics-2e/pages/6-section-summary
Kepler’s first law
https://openstax.org/books/college-physics-2e/pages/6-section-summary
The orbit of each planet about the Sun is an ellipse with the Sun at one focus.
https://openstax.org/books/college-physics-2e/pages/6-section-summary
Kepler’s second law
https://openstax.org/books/college-physics-2e/pages/6-section-summary
Each planet moves so that an imaginary line drawn from the Sun to the planet sweeps out equal areas in equal times.
https://openstax.org/books/college-physics-2e/pages/6-section-summary
Kepler’s third law
https://openstax.org/books/college-physics-2e/pages/6-section-summary
The ratio of the squares of the periods of any two planets about the Sun is equal to the ratio of the cubes of their average distances from the Sun:
https://openstax.org/books/college-physics-2e/pages/6-section-summary
whereTTis the period (time for one orbit) andrris the average radius of the orbit.
https://openstax.org/books/college-physics-2e/pages/6-section-summary
The period and radius of a satellite’s orbit about a larger bodyMMare related byT2=4π2GMr3T2=4π2GMr3orr3T2=G4π2M.r3T2=G4π2M.
https://openstax.org/books/college-physics-2e/pages/6-section-summary
or
https://openstax.org/books/college-physics-2e/pages/6-section-summary
basal metabolic rate : the total energy conversion rate of a person at rest
https://openstax.org/books/college-physics-2e/pages/7-glossary
chemical energy : the energy in a substance stored in the bonds between atoms and molecules that can be released in a chemical reaction
https://openstax.org/books/college-physics-2e/pages/7-glossary
conservation of mechanical energy : the rule that the sum of the kinetic energies and potential energies remains constant if only conservative forces act on and within a system
https://openstax.org/books/college-physics-2e/pages/7-glossary
conservative force : a force that does the same work for any given initial and final configuration, regardless of the path followed
https://openstax.org/books/college-physics-2e/pages/7-glossary
efficiency : a measure of the effectiveness of the input of energy to do work; useful energy or work divided by the total input of energy
https://openstax.org/books/college-physics-2e/pages/7-glossary
electrical energy : the energy carried by a flow of charge
https://openstax.org/books/college-physics-2e/pages/7-glossary
energy : the ability to do work
https://openstax.org/books/college-physics-2e/pages/7-glossary
fossil fuels : oil, natural gas, and coal
https://openstax.org/books/college-physics-2e/pages/7-glossary
friction : the force between surfaces that opposes one sliding on the other; friction changes mechanical energy into thermal energy
https://openstax.org/books/college-physics-2e/pages/7-glossary
gravitational potential energy : the energy an object has due to its position in a gravitational field
https://openstax.org/books/college-physics-2e/pages/7-glossary
horsepower : an older non-SI unit of power, with1 hp=746 W1 hp=746 W
https://openstax.org/books/college-physics-2e/pages/7-glossary
joule : SI unit of work and energy, equal to one newton-meter
https://openstax.org/books/college-physics-2e/pages/7-glossary
kilowatt-hour : (kWâ‹h)(kWâ‹h)unit used primarily for electrical energy provided by electric utility companies
https://openstax.org/books/college-physics-2e/pages/7-glossary
kinetic energy : the energy an object has by reason of its motion, equal to12mv212mv2for the translational (i.e., non-rotational) motion of an object of massmmmoving at speedvv
https://openstax.org/books/college-physics-2e/pages/7-glossary
law of conservation of energy : the general law that total energy is constant in any process; energy may change in form or be transferred from one system to another, but the total remains the same
https://openstax.org/books/college-physics-2e/pages/7-glossary
mechanical energy : the sum of kinetic energy and potential energy
https://openstax.org/books/college-physics-2e/pages/7-glossary
metabolic rate : the rate at which the body uses food energy to sustain life and to do different activities
https://openstax.org/books/college-physics-2e/pages/7-glossary
net work : work done by the net force, or vector sum of all the forces, acting on an object
https://openstax.org/books/college-physics-2e/pages/7-glossary
nonconservative force : a force whose work depends on the path followed between the given initial and final configurations
https://openstax.org/books/college-physics-2e/pages/7-glossary
nuclear energy : energy released by changes within atomic nuclei, such as the fusion of two light nuclei or the fission of a heavy nucleus
https://openstax.org/books/college-physics-2e/pages/7-glossary
potential energy : energy due to position, shape, or configuration
https://openstax.org/books/college-physics-2e/pages/7-glossary
potential energy of a spring : the stored energy of a spring as a function of its displacement; when Hooke’s law applies, it is given by the expression12kx212kx2wherexxis the distance the spring is compressed or extended andkkis the spring constant
https://openstax.org/books/college-physics-2e/pages/7-glossary
power : the rate at which work is done
https://openstax.org/books/college-physics-2e/pages/7-glossary
radiant energy : the energy carried by electromagnetic waves
https://openstax.org/books/college-physics-2e/pages/7-glossary
renewable forms of energy : those sources that cannot be used up, such as water, wind, solar, and biomass
https://openstax.org/books/college-physics-2e/pages/7-glossary
thermal energy : the energy within an object due to the random motion of its atoms and molecules that accounts for the object's temperature
https://openstax.org/books/college-physics-2e/pages/7-glossary
useful work : work done on an external system
https://openstax.org/books/college-physics-2e/pages/7-glossary
watt : (W) SI unit of power, with1 W=1 J/s1 W=1 J/s
https://openstax.org/books/college-physics-2e/pages/7-glossary
work : the transfer of energy by a force that causes an object to be displaced; the product of the component of the force in the direction of the displacement and the magnitude of the displacement
https://openstax.org/books/college-physics-2e/pages/7-glossary
work-energy theorem : the result, based on Newton’s laws, that the net work done on an object is equal to its change in kinetic energy
https://openstax.org/books/college-physics-2e/pages/7-glossary
Work is the transfer of energy by a force acting on an object as it is displaced.
https://openstax.org/books/college-physics-2e/pages/7-section-summary
The workWWthat a forceFFdoes on an object is the product of the magnitudeFFof the force, times the magnitudeddof the displacement, times the cosine of the angleθθbetween them. In symbols,W=Fdcosθ.W=Fdcosθ.
https://openstax.org/books/college-physics-2e/pages/7-section-summary
The SI unit for work and energy is the joule (J), where1J=1Nâ‹m=1 kgâ‹m2/s21J=1Nâ‹m=1 kgâ‹m2/s2.
https://openstax.org/books/college-physics-2e/pages/7-section-summary