answer string | choices dict | id string | kind string | lang string | question string | steps list | subject string | text string | topic string |
|---|---|---|---|---|---|---|---|---|---|
Temperature is 300 K. | {
"A": "299 K",
"B": "301 K",
"C": "302 K",
"D": "300 K"
} | phy_0801 | multiple_choice | en | Room temperature is 27 °C. What is it in kelvin? | [
"27 °C + 273.",
"= 300 K.",
"Select option D."
] | physics | Answer: 300 K
Steps:
1. 27 °C + 273.
2. = 300 K.
3. Select option D.
Answer: (D) | thermodynamics |
Apparent depth is 90 cm. | {
"A": "85 cm",
"B": "90 cm",
"C": "95 cm",
"D": "100 cm"
} | phy_0802 | multiple_choice | en | An object sits 135 cm deep in glass (n = 1.5). What is the apparent depth? | [
"d' = 135 cm / 1.5.",
"d' = 90 cm.",
"Select option B."
] | physics | Answer: 90 cm
Steps:
1. d' = 135 cm / 1.5.
2. d' = 90 cm.
3. Select option B.
Answer: (B) | optics |
Period is 0.11 s. | {
"A": "0.11 s",
"B": "0.1 s",
"C": "0.09 s",
"D": "0.12 s"
} | phy_0803 | multiple_choice | en | A wave has frequency 9 Hz. What is its period? | [
"T = 1 / 9 Hz.",
"T = 0.11 s.",
"Select option A."
] | physics | Answer: 0.11 s
Steps:
1. T = 1 / 9 Hz.
2. T = 0.11 s.
3. Select option A.
Answer: (A) | waves |
Mass number: 35. | null | phy_0804 | worked_example | en | A nucleus has 17 protons and 18 neutrons. Compute its mass number. | [
"A = Z+N.",
"A = 17 + 18.",
"= 35."
] | physics | Answer: Mass number: 35.
Steps:
1. A = Z+N.
2. A = 17 + 18.
3. = 35. | modern |
Momentum: 54 kg·m/s. | null | phy_0805 | worked_example | en | A mass of 18 kg moves at 3 m/s. Compute its momentum. | [
"p = m×v.",
"p = 18 kg × 3 m/s.",
"= 54 kg·m/s."
] | physics | Answer: Momentum: 54 kg·m/s.
Steps:
1. p = m×v.
2. p = 18 kg × 3 m/s.
3. = 54 kg·m/s. | mechanics |
Energy: 1900 J. | null | phy_0806 | worked_example | en | A 100 W heater runs for 19 s. Compute the energy used. | [
"E = P×t.",
"E = 100 W × 19 s.",
"= 1900 J."
] | physics | Answer: Energy: 1900 J.
Steps:
1. E = P×t.
2. E = 100 W × 19 s.
3. = 1900 J. | electromagnetism |
Entropie počítá mikroskopický nepořádek. | null | phy_0807 | concept | cs | Co je entropie? | [
"Entropie počítá mikroskopický nepořádek.",
"Odpověď tedy platí: Entropie počítá mikroskopický nepořádek."
] | physics | Answer: Entropie počítá mikroskopický nepořádek.
Steps:
1. Entropie počítá mikroskopický nepořádek.
2. Odpověď tedy platí: Entropie počítá mikroskopický nepořádek. | thermodynamics |
Kapky lámou a odrážejí světlo pod 42 stupni. | null | phy_0808 | concept | cs | Proč duha? | [
"Kapky lámou a odrážejí světlo pod 42 stupni.",
"Odpověď tedy platí: Kapky lámou a odrážejí světlo pod 42 stupni."
] | physics | Answer: Kapky lámou a odrážejí světlo pod 42 stupni.
Steps:
1. Kapky lámou a odrážejí světlo pod 42 stupni.
2. Odpověď tedy platí: Kapky lámou a odrážejí světlo pod 42 stupni. | optics |
Particles outpacing light in water trail blue optical booms. | null | phy_0809 | concept | en | Why Cherenkov glow? | [
"Particles outpacing light in water trail blue optical booms.",
"So the answer stands: Particles outpacing light in water trail blue optical booms."
] | physics | Answer: Particles outpacing light in water trail blue optical booms.
Steps:
1. Particles outpacing light in water trail blue optical booms.
2. So the answer stands: Particles outpacing light in water trail blue optical booms. | waves |
Nestabilní jádra se rozpadají s poločasy. | null | phy_0810 | concept | cs | Co je radioaktivita? | [
"Nestabilní jádra se rozpadají s poločasy.",
"Odpověď tedy platí: Nestabilní jádra se rozpadají s poločasy."
] | physics | Answer: Nestabilní jádra se rozpadají s poločasy.
Steps:
1. Nestabilní jádra se rozpadají s poločasy.
2. Odpověď tedy platí: Nestabilní jádra se rozpadají s poločasy. | modern |
The Moon's uneven pull bulges oceans twice daily, dragging high waters around. | null | phy_0811 | concept | en | Why tides? | [
"The Moon's uneven pull bulges oceans twice daily, dragging high waters around.",
"So the answer stands: The Moon's uneven pull bulges oceans twice daily, dragging high waters around."
] | physics | Answer: The Moon's uneven pull bulges oceans twice daily, dragging high waters around.
Steps:
1. The Moon's uneven pull bulges oceans twice daily, dragging high waters around.
2. So the answer stands: The Moon's uneven pull bulges oceans twice daily, dragging high waters around. | mechanics |
Energie: 800 J. | null | phy_0812 | worked_example | cs | Topidlo 100 W běží po 8 s. Spočítej spotřebovanou energii. | [
"E = P×t.",
"E = 100 W × 8 s.",
"= 800 J."
] | physics | Answer: Energie: 800 J.
Steps:
1. E = P×t.
2. E = 100 W × 8 s.
3. = 800 J. | electromagnetism |
Peak wavelength shrinks as temperature rises, from red coals to blue stars. | null | phy_0813 | concept | en | What is Wien's law? | [
"Peak wavelength shrinks as temperature rises, from red coals to blue stars.",
"So the answer stands: Peak wavelength shrinks as temperature rises, from red coals to blue stars."
] | physics | Answer: Peak wavelength shrinks as temperature rises, from red coals to blue stars.
Steps:
1. Peak wavelength shrinks as temperature rises, from red coals to blue stars.
2. So the answer stands: Peak wavelength shrinks as temperature rises, from red coals to blue stars. | thermodynamics |
A living camera focusing light onto retinas with lens and iris. | null | phy_0814 | concept | en | What is the eye? | [
"A living camera focusing light onto retinas with lens and iris.",
"So the answer stands: A living camera focusing light onto retinas with lens and iris."
] | physics | Answer: A living camera focusing light onto retinas with lens and iris.
Steps:
1. A living camera focusing light onto retinas with lens and iris.
2. So the answer stands: A living camera focusing light onto retinas with lens and iris. | optics |
3rd harmonic: 720 Hz. | null | phy_0815 | worked_example | en | A string's fundamental is 240 Hz. Compute its 3rd harmonic. | [
"f3 = 3×f1.",
"f3 = 3 × 240 Hz.",
"= 720 Hz."
] | physics | Answer: 3rd harmonic: 720 Hz.
Steps:
1. f3 = 3×f1.
2. f3 = 3 × 240 Hz.
3. = 720 Hz. | waves |
Survivors: 3200. | null | phy_0816 | worked_example | en | A sample of 12800 atoms undergoes 2 half-lives. Compute the survivors. | [
"Halve: 12800 → 6400.",
"Halve: 6400 → 3200.",
"= 3200."
] | physics | Answer: Survivors: 3200.
Steps:
1. Halve: 12800 → 6400.
2. Halve: 6400 → 3200.
3. = 3200. | modern |
Net force: 34 N. | null | phy_0817 | worked_example | en | A mass of 17 kg accelerates at 2 m/s². Compute the net force. | [
"F = m×a.",
"F = 17 kg × 2 m/s².",
"= 34 N."
] | physics | Answer: Net force: 34 N.
Steps:
1. F = m×a.
2. F = 17 kg × 2 m/s².
3. = 34 N. | mechanics |
Výkon: 75 W. | null | phy_0818 | worked_example | cs | Proud 5 A teče přes 3 Ω. Spočítej ztrátový výkon. | [
"P = I²×R.",
"P = (5 A)² × 3 Ω.",
"= 75 W."
] | physics | Answer: Výkon: 75 W.
Steps:
1. P = I²×R.
2. P = (5 A)² × 3 Ω.
3. = 75 W. | electromagnetism |
Heat needed is 37674 J. | {
"A": "37674 J",
"B": "33488 J",
"C": "41860 J",
"D": "46046 J"
} | phy_0819 | multiple_choice | en | How much heat warms 1 kg of water by 9 K? (c = 4186 J/(kg·K)) | [
"Q = 1 kg × 4186 J/(kg·K) × 9 K.",
"Q = 37674 J.",
"Select option A."
] | physics | Answer: 37674 J
Steps:
1. Q = 1 kg × 4186 J/(kg·K) × 9 K.
2. Q = 37674 J.
3. Select option A.
Answer: (A) | thermodynamics |
Magnification is 10×. | {
"A": "10×",
"B": "9×",
"C": "11×",
"D": "12×"
} | phy_0820 | multiple_choice | en | An image forms 100 cm from a lens, object at 10 cm. What is the magnification? | [
"M = 100 cm / 10 cm.",
"M = 10×.",
"Select option A."
] | physics | Answer: 10×
Steps:
1. M = 100 cm / 10 cm.
2. M = 10×.
3. Select option A.
Answer: (A) | optics |
3rd harmonic is 540 Hz. | {
"A": "510 Hz",
"B": "540 Hz",
"C": "570 Hz",
"D": "600 Hz"
} | phy_0821 | multiple_choice | en | A string's fundamental is 180 Hz. What is its 3rd harmonic? | [
"f3 = 3 × 180 Hz.",
"f3 = 540 Hz.",
"Select option B."
] | physics | Answer: 540 Hz
Steps:
1. f3 = 3 × 180 Hz.
2. f3 = 540 Hz.
3. Select option B.
Answer: (B) | waves |
Lines: 171. | null | phy_0822 | worked_example | en | An atom is excited to level n = 19. Count the spectral lines it can emit. | [
"Pairs: 19×18/2.",
"= 342/2.",
"= 171."
] | physics | Answer: Lines: 171.
Steps:
1. Pairs: 19×18/2.
2. = 342/2.
3. = 171. | modern |
Work: 320 J. | null | phy_0823 | worked_example | en | A force of 80 N pushes 4 m. Compute the work done. | [
"W = F×d.",
"W = 80 N × 4 m.",
"= 320 J."
] | physics | Answer: Work: 320 J.
Steps:
1. W = F×d.
2. W = 80 N × 4 m.
3. = 320 J. | mechanics |
Swirling induced currents brake trains and heat induction stoves. | null | phy_0824 | concept | en | Why eddy currents? | [
"Swirling induced currents brake trains and heat induction stoves.",
"So the answer stands: Swirling induced currents brake trains and heat induction stoves."
] | physics | Answer: Swirling induced currents brake trains and heat induction stoves.
Steps:
1. Swirling induced currents brake trains and heat induction stoves.
2. So the answer stands: Swirling induced currents brake trains and heat induction stoves. | electromagnetism |
Efficiency is 90%. | {
"A": "80%",
"B": "90%",
"C": "100%",
"D": "110%"
} | phy_0825 | multiple_choice | en | An engine turns 900 J of 1000 J heat into work. What is its efficiency? | [
"900 J / 1000 J.",
"= 90%.",
"Select option B."
] | physics | Answer: 90%
Steps:
1. 900 J / 1000 J.
2. = 90%.
3. Select option B.
Answer: (B) | thermodynamics |
Apparent depth: 160 cm. | null | phy_0826 | worked_example | en | An object sits 240 cm deep in glass (n = 1.5). Compute the apparent depth. | [
"d' = d/n.",
"d' = 240 cm / 1.5.",
"= 160 cm."
] | physics | Answer: Apparent depth: 160 cm.
Steps:
1. d' = d/n.
2. d' = 240 cm / 1.5.
3. = 160 cm. | optics |
Rippling spacetime from colliding black holes, detected by LIGO. | null | phy_0827 | concept | en | What are gravitational waves? | [
"Rippling spacetime from colliding black holes, detected by LIGO.",
"So the answer stands: Rippling spacetime from colliding black holes, detected by LIGO."
] | physics | Answer: Rippling spacetime from colliding black holes, detected by LIGO.
Steps:
1. Rippling spacetime from colliding black holes, detected by LIGO.
2. So the answer stands: Rippling spacetime from colliding black holes, detected by LIGO. | waves |
Count: 28. | {
"A": "27",
"B": "29",
"C": "28",
"D": "30"
} | phy_0828 | multiple_choice | en | An atom is excited to level n = 8. How many spectral lines can it emit? | [
"Pairs: 8×7/2.",
"Lines: 28.",
"Select option C."
] | physics | Answer: 28
Steps:
1. Pairs: 8×7/2.
2. Lines: 28.
3. Select option C.
Answer: (C) | modern |
Falling drag grows with speed until balancing weight, capping fall rate steadily. | null | phy_0829 | concept | en | What is terminal velocity? | [
"Falling drag grows with speed until balancing weight, capping fall rate steadily.",
"So the answer stands: Falling drag grows with speed until balancing weight, capping fall rate steadily."
] | physics | Answer: Falling drag grows with speed until balancing weight, capping fall rate steadily.
Steps:
1. Falling drag grows with speed until balancing weight, capping fall rate steadily.
2. So the answer stands: Falling drag grows with speed until balancing weight, capping fall rate steadily. | mechanics |
Power: 768 W. | null | phy_0830 | worked_example | en | A current of 16 A flows through 3 Ω. Compute the dissipated power. | [
"P = I²×R.",
"P = (16 A)² × 3 Ω.",
"= 768 W."
] | physics | Answer: Power: 768 W.
Steps:
1. P = I²×R.
2. P = (16 A)² × 3 Ω.
3. = 768 W. | electromagnetism |
Temperature is 301 K. | {
"A": "301 K",
"B": "300 K",
"C": "302 K",
"D": "303 K"
} | phy_0831 | multiple_choice | en | Room temperature is 28 °C. What is it in kelvin? | [
"28 °C + 273.",
"= 301 K.",
"Select option A."
] | physics | Answer: 301 K
Steps:
1. 28 °C + 273.
2. = 301 K.
3. Select option A.
Answer: (A) | thermodynamics |
Time is 9 s. | {
"A": "10 s",
"B": "9 s",
"C": "11 s",
"D": "8 s"
} | phy_0832 | multiple_choice | en | Light travels 27×10⁸ m. How many seconds does it take? (c = 3×10⁸ m/s) | [
"t = 27×10⁸ m / 3×10⁸ m/s.",
"t = 9 s.",
"Select option B."
] | physics | Answer: 9 s
Steps:
1. t = 27×10⁸ m / 3×10⁸ m/s.
2. t = 9 s.
3. Select option B.
Answer: (B) | optics |
Speed: 2850 m/s. | null | phy_0833 | worked_example | en | A string wave has f = 950 Hz and λ = 3 m. Compute its speed. | [
"v = f×λ.",
"v = 950 Hz × 3 m.",
"= 2850 m/s."
] | physics | Answer: Speed: 2850 m/s.
Steps:
1. v = f×λ.
2. v = 950 Hz × 3 m.
3. = 2850 m/s. | waves |
No two fermions share one state, building chemistry's table. | null | phy_0834 | concept | en | Why Pauli exclusion? | [
"No two fermions share one state, building chemistry's table.",
"So the answer stands: No two fermions share one state, building chemistry's table."
] | physics | Answer: No two fermions share one state, building chemistry's table.
Steps:
1. No two fermions share one state, building chemistry's table.
2. So the answer stands: No two fermions share one state, building chemistry's table. | modern |
Net force is 30 N. | {
"A": "30 N",
"B": "27 N",
"C": "33 N",
"D": "36 N"
} | phy_0835 | multiple_choice | en | A mass of 10 kg accelerates at 3 m/s². What is the net force? | [
"F = 10 kg × 3 m/s².",
"F = 30 N.",
"Select option A."
] | physics | Answer: 30 N
Steps:
1. F = 10 kg × 3 m/s².
2. F = 30 N.
3. Select option A.
Answer: (A) | mechanics |
Voltage is 45 V. | {
"A": "40 V",
"B": "50 V",
"C": "55 V",
"D": "45 V"
} | phy_0836 | multiple_choice | en | A current of 9 A flows through 5 Ω. What is the voltage? | [
"V = 9 A × 5 Ω.",
"V = 45 V.",
"Select option D."
] | physics | Answer: 45 V
Steps:
1. V = 9 A × 5 Ω.
2. V = 45 V.
3. Select option D.
Answer: (D) | electromagnetism |
Glass passes sunlight but traps infrared, warming planets and houses. | null | phy_0837 | concept | en | Why greenhouse effect? | [
"Glass passes sunlight but traps infrared, warming planets and houses.",
"So the answer stands: Glass passes sunlight but traps infrared, warming planets and houses."
] | physics | Answer: Glass passes sunlight but traps infrared, warming planets and houses.
Steps:
1. Glass passes sunlight but traps infrared, warming planets and houses.
2. So the answer stands: Glass passes sunlight but traps infrared, warming planets and houses. | thermodynamics |
Apparent depth is 100 cm. | {
"A": "95 cm",
"B": "105 cm",
"C": "100 cm",
"D": "110 cm"
} | phy_0838 | multiple_choice | en | An object sits 150 cm deep in glass (n = 1.5). What is the apparent depth? | [
"d' = 150 cm / 1.5.",
"d' = 100 cm.",
"Select option C."
] | physics | Answer: 100 cm
Steps:
1. d' = 150 cm / 1.5.
2. d' = 100 cm.
3. Select option C.
Answer: (C) | optics |
3. harmonická: 360 Hz. | null | phy_0839 | worked_example | cs | Základ struny je 120 Hz. Spočítej její 3. harmonickou. | [
"f3 = 3×f1.",
"f3 = 3 × 120 Hz.",
"= 360 Hz."
] | physics | Answer: 3. harmonická: 360 Hz.
Steps:
1. f3 = 3×f1.
2. f3 = 3 × 120 Hz.
3. = 360 Hz. | waves |
Mass number: 37. | null | phy_0840 | worked_example | en | A nucleus has 18 protons and 19 neutrons. Compute its mass number. | [
"A = Z+N.",
"A = 18 + 19.",
"= 37."
] | physics | Answer: Mass number: 37.
Steps:
1. A = Z+N.
2. A = 18 + 19.
3. = 37. | modern |
Tilted roads supply inward force from normals, letting cars corner without sliding. | null | phy_0841 | concept | en | Why banked curves? | [
"Tilted roads supply inward force from normals, letting cars corner without sliding.",
"So the answer stands: Tilted roads supply inward force from normals, letting cars corner without sliding."
] | physics | Answer: Tilted roads supply inward force from normals, letting cars corner without sliding.
Steps:
1. Tilted roads supply inward force from normals, letting cars corner without sliding.
2. So the answer stands: Tilted roads supply inward force from normals, letting cars corner without sliding. | mechanics |
Power is 120 W. | {
"A": "120 W",
"B": "108 W",
"C": "132 W",
"D": "144 W"
} | phy_0842 | multiple_choice | en | A bulb runs at 12 V drawing 10 A. What is its power? | [
"P = 12 V × 10 A.",
"P = 120 W.",
"Select option A."
] | physics | Answer: 120 W
Steps:
1. P = 12 V × 10 A.
2. P = 120 W.
3. Select option A.
Answer: (A) | electromagnetism |
It moves more heat than work spent, heating homes efficiently. | null | phy_0843 | concept | en | What is a heat pump? | [
"It moves more heat than work spent, heating homes efficiently.",
"So the answer stands: It moves more heat than work spent, heating homes efficiently."
] | physics | Answer: It moves more heat than work spent, heating homes efficiently.
Steps:
1. It moves more heat than work spent, heating homes efficiently.
2. So the answer stands: It moves more heat than work spent, heating homes efficiently. | thermodynamics |
Magnification: 17×. | null | phy_0844 | worked_example | en | An image forms 170 cm from a lens, object at 10 cm. Compute the magnification. | [
"M = di/do.",
"M = 170 cm / 10 cm.",
"= 17×."
] | physics | Answer: Magnification: 17×.
Steps:
1. M = di/do.
2. M = 170 cm / 10 cm.
3. = 17×. | optics |
Distance: 5780 m. | null | phy_0845 | worked_example | en | Thunder is heard 17 s after lightning. How far away is the storm? (v = 340 m/s) | [
"d = v×t.",
"d = 340 m/s × 17 s.",
"= 5780 m."
] | physics | Answer: Distance: 5780 m.
Steps:
1. d = v×t.
2. d = 340 m/s × 17 s.
3. = 5780 m. | waves |
Mass number is 14. | {
"A": "13",
"B": "15",
"C": "16",
"D": "14"
} | phy_0846 | multiple_choice | en | A nucleus has 7 protons and 7 neutrons. What is its mass number? | [
"A = 7 + 7.",
"A = 14.",
"Select option D."
] | physics | Answer: 14
Steps:
1. A = 7 + 7.
2. A = 14.
3. Select option D.
Answer: (D) | modern |
Speed is 18 m/s. | {
"A": "17 m/s",
"B": "18 m/s",
"C": "19 m/s",
"D": "20 m/s"
} | phy_0847 | multiple_choice | en | A car travels 180 m in 10 s. What is its speed? | [
"v = 180 m / 10 s.",
"v = 18 m/s.",
"Select option B."
] | physics | Answer: 18 m/s
Steps:
1. v = 180 m / 10 s.
2. v = 18 m/s.
3. Select option B.
Answer: (B) | mechanics |
Napětí: 60 V. | null | phy_0848 | worked_example | cs | Proud 5 A teče přes 12 Ω. Spočítej napětí. | [
"U = I×R.",
"U = 5 A × 12 Ω.",
"= 60 V."
] | physics | Answer: Napětí: 60 V.
Steps:
1. U = I×R.
2. U = 5 A × 12 Ω.
3. = 60 V. | electromagnetism |
Heat: 125580 J. | null | phy_0849 | worked_example | en | How much heat warms 2 kg of water by 15 K? (c = 4186 J/(kg·K)) | [
"Q = 2 kg × 4186 J/(kg·K) × 15 K.",
"= 125580 J."
] | physics | Answer: Heat: 125580 J.
Steps:
1. Q = 2 kg × 4186 J/(kg·K) × 15 K.
2. = 125580 J. | thermodynamics |
Odpověď je lom. | {
"A": "lom",
"B": "odraz",
"C": "vyvržení",
"D": "vstříknutí"
} | phy_0850 | multiple_choice | cs | Vyber: co se ohýbá na rozhraní? | [
"Rychlosti se liší.",
"Tedy: lom.",
"Vyber možnost A."
] | physics | Answer: lom
Steps:
1. Rychlosti se liší.
2. Tedy: lom.
3. Vyber možnost A.
Answer: (A) | optics |
Sladěné buzení buduje obrovské kmitání. | null | phy_0851 | concept | cs | Co je rezonance? | [
"Sladěné buzení buduje obrovské kmitání.",
"Odpověď tedy platí: Sladěné buzení buduje obrovské kmitání."
] | physics | Answer: Sladěné buzení buduje obrovské kmitání.
Steps:
1. Sladěné buzení buduje obrovské kmitání.
2. Odpověď tedy platí: Sladěné buzení buduje obrovské kmitání. | waves |
Vacuum fluctuations push close plates together measurably. | null | phy_0852 | concept | en | What is the Casimir effect? | [
"Vacuum fluctuations push close plates together measurably.",
"So the answer stands: Vacuum fluctuations push close plates together measurably."
] | physics | Answer: Vacuum fluctuations push close plates together measurably.
Steps:
1. Vacuum fluctuations push close plates together measurably.
2. So the answer stands: Vacuum fluctuations push close plates together measurably. | modern |
Kinetická energie je 25 J. | {
"A": "20 J",
"B": "30 J",
"C": "35 J",
"D": "25 J"
} | phy_0853 | multiple_choice | cs | Míč 2 kg letí 5 m/s. Jaká je jeho kinetická energie? | [
"KE = ½×2 kg×(5 m/s)².",
"KE = 25 J.",
"Vyber možnost D."
] | physics | Answer: 25 J
Steps:
1. KE = ½×2 kg×(5 m/s)².
2. KE = 25 J.
3. Vyber možnost D.
Answer: (D) | mechanics |
Charge is 180 C. | {
"A": "160 C",
"B": "180 C",
"C": "200 C",
"D": "220 C"
} | phy_0854 | multiple_choice | en | A current of 4 A flows for 45 s. How much charge passes? | [
"Q = 4 A × 45 s.",
"Q = 180 C.",
"Select option B."
] | physics | Answer: 180 C
Steps:
1. Q = 4 A × 45 s.
2. Q = 180 C.
3. Select option B.
Answer: (B) | electromagnetism |
Teplo: 33488 J. | null | phy_0855 | worked_example | cs | Kolik tepla ohřeje 2 kg vody o 4 K? (c = 4186 J/(kg·K)) | [
"Q = 2 kg × 4186 J/(kg·K) × 4 K.",
"= 33488 J."
] | physics | Answer: Teplo: 33488 J.
Steps:
1. Q = 2 kg × 4186 J/(kg·K) × 4 K.
2. = 33488 J. | thermodynamics |
Magnification is 11×. | {
"A": "10×",
"B": "11×",
"C": "12×",
"D": "13×"
} | phy_0856 | multiple_choice | en | An image forms 110 cm from a lens, object at 10 cm. What is the magnification? | [
"M = 110 cm / 10 cm.",
"M = 11×.",
"Select option B."
] | physics | Answer: 11×
Steps:
1. M = 110 cm / 10 cm.
2. M = 11×.
3. Select option B.
Answer: (B) | optics |
Speed is 1000 m/s. | {
"A": "1000 m/s",
"B": "950 m/s",
"C": "1050 m/s",
"D": "1100 m/s"
} | phy_0857 | multiple_choice | en | A string wave has f = 500 Hz and λ = 2 m. What is its speed? | [
"v = 500 Hz × 2 m.",
"v = 1000 m/s.",
"Select option A."
] | physics | Answer: 1000 m/s
Steps:
1. v = 500 Hz × 2 m.
2. v = 1000 m/s.
3. Select option A.
Answer: (A) | waves |
Survivors: 3400. | null | phy_0858 | worked_example | en | A sample of 13600 atoms undergoes 2 half-lives. Compute the survivors. | [
"Halve: 13600 → 6800.",
"Halve: 6800 → 3400.",
"= 3400."
] | physics | Answer: Survivors: 3400.
Steps:
1. Halve: 13600 → 6800.
2. Halve: 6800 → 3400.
3. = 3400. | modern |
Momentum: 57 kg·m/s. | null | phy_0859 | worked_example | en | A mass of 19 kg moves at 3 m/s. Compute its momentum. | [
"p = m×v.",
"p = 19 kg × 3 m/s.",
"= 57 kg·m/s."
] | physics | Answer: Momentum: 57 kg·m/s.
Steps:
1. p = m×v.
2. p = 19 kg × 3 m/s.
3. = 57 kg·m/s. | mechanics |
Náboj je 60 C. | {
"A": "40 C",
"B": "80 C",
"C": "100 C",
"D": "60 C"
} | phy_0860 | multiple_choice | cs | Proud 4 A teče po 15 s. Kolik náboje projde? | [
"Q = 4 A × 15 s.",
"Q = 60 C.",
"Vyber možnost D."
] | physics | Answer: 60 C
Steps:
1. Q = 4 A × 15 s.
2. Q = 60 C.
3. Vyber možnost D.
Answer: (D) | electromagnetism |
Power: 190 W. | null | phy_0861 | worked_example | en | An engine does 1900 J of work in 10 s. Compute its power. | [
"P = W/t.",
"P = 1900 J / 10 s.",
"= 190 W."
] | physics | Answer: Power: 190 W.
Steps:
1. P = W/t.
2. P = 1900 J / 10 s.
3. = 190 W. | thermodynamics |
Time: 15.3 s. | null | phy_0862 | worked_example | en | Light travels 46×10⁸ m. Compute the travel time. (c = 3×10⁸ m/s) | [
"t = d/c.",
"t = 46×10⁸ / 3×10⁸ s.",
"= 15.3 s."
] | physics | Answer: Time: 15.3 s.
Steps:
1. t = d/c.
2. t = 46×10⁸ / 3×10⁸ s.
3. = 15.3 s. | optics |
Rychlost: 1050 m/s. | null | phy_0863 | worked_example | cs | Vlna na struně má f = 350 Hz a λ = 3 m. Spočítej její rychlost. | [
"v = f×λ.",
"v = 350 Hz × 3 m.",
"= 1050 m/s."
] | physics | Answer: Rychlost: 1050 m/s.
Steps:
1. v = f×λ.
2. v = 350 Hz × 3 m.
3. = 1050 m/s. | waves |
Lines: 190. | null | phy_0864 | worked_example | en | An atom is excited to level n = 20. Count the spectral lines it can emit. | [
"Pairs: 20×19/2.",
"= 380/2.",
"= 190."
] | physics | Answer: Lines: 190.
Steps:
1. Pairs: 20×19/2.
2. = 380/2.
3. = 190. | modern |
Odpověď je F rovná se ma. | {
"A": "F rovná se ma",
"B": "E rovná se mc",
"C": "V rovná se IR",
"D": "pV rovná se nRT"
} | phy_0865 | multiple_choice | cs | Vyber: co váže tlak a pohyb? | [
"Druhý zákon váže.",
"Tedy: F rovná se ma.",
"Vyber možnost A."
] | physics | Answer: F rovná se ma
Steps:
1. Druhý zákon váže.
2. Tedy: F rovná se ma.
3. Vyber možnost A.
Answer: (A) | mechanics |
High frequencies crowd to surfaces, raising effective AC resistance. | null | phy_0866 | concept | en | What is skin effect? | [
"High frequencies crowd to surfaces, raising effective AC resistance.",
"So the answer stands: High frequencies crowd to surfaces, raising effective AC resistance."
] | physics | Answer: High frequencies crowd to surfaces, raising effective AC resistance.
Steps:
1. High frequencies crowd to surfaces, raising effective AC resistance.
2. So the answer stands: High frequencies crowd to surfaces, raising effective AC resistance. | electromagnetism |
Výkon: 80 W. | null | phy_0867 | worked_example | cs | Motor vykoná 800 J práce za 10 s. Spočítej jeho výkon. | [
"P = W/t.",
"P = 800 J / 10 s.",
"= 80 W."
] | physics | Answer: Výkon: 80 W.
Steps:
1. P = W/t.
2. P = 800 J / 10 s.
3. = 80 W. | thermodynamics |
Odpověď je difrakce. | {
"A": "odraz",
"B": "difrakce",
"C": "pohlcení",
"D": "emise"
} | phy_0868 | multiple_choice | cs | Vyber: co dokazuje vlnění? | [
"Okraje třásněny.",
"Tedy: difrakce.",
"Vyber možnost B."
] | physics | Answer: difrakce
Steps:
1. Okraje třásněny.
2. Tedy: difrakce.
3. Vyber možnost B.
Answer: (B) | optics |
Kilometre lasers sense sub-proton arm shifts from passing waves. | null | phy_0869 | concept | en | Why LIGO works? | [
"Kilometre lasers sense sub-proton arm shifts from passing waves.",
"So the answer stands: Kilometre lasers sense sub-proton arm shifts from passing waves."
] | physics | Answer: Kilometre lasers sense sub-proton arm shifts from passing waves.
Steps:
1. Kilometre lasers sense sub-proton arm shifts from passing waves.
2. So the answer stands: Kilometre lasers sense sub-proton arm shifts from passing waves. | waves |
700 atoms remain. | {
"A": "650",
"B": "750",
"C": "700",
"D": "800"
} | phy_0870 | multiple_choice | en | A sample of 2800 atoms undergoes 2 half-lives. How many remain? | [
"Halve twice: 2800 → 1400 → 700.",
"Left: 700.",
"Select option C."
] | physics | Answer: 700
Steps:
1. Halve twice: 2800 → 1400 → 700.
2. Left: 700.
3. Select option C.
Answer: (C) | modern |
Net force: 36 N. | null | phy_0871 | worked_example | en | A mass of 18 kg accelerates at 2 m/s². Compute the net force. | [
"F = m×a.",
"F = 18 kg × 2 m/s².",
"= 36 N."
] | physics | Answer: Net force: 36 N.
Steps:
1. F = m×a.
2. F = 18 kg × 2 m/s².
3. = 36 N. | mechanics |
Voltage: 192 V. | null | phy_0872 | worked_example | en | A current of 16 A flows through 12 Ω. Compute the voltage. | [
"V = I×R.",
"V = 16 A × 12 Ω.",
"= 192 V."
] | physics | Answer: Voltage: 192 V.
Steps:
1. V = I×R.
2. V = 16 A × 12 Ω.
3. = 192 V. | electromagnetism |
Temperature: 303 K. | null | phy_0873 | worked_example | en | Temperature is 30 °C. Convert it to kelvin. | [
"Add 273.",
"30 + 273.",
"= 303 K."
] | physics | Answer: Temperature: 303 K.
Steps:
1. Add 273.
2. 30 + 273.
3. = 303 K. | thermodynamics |
Extra lenses correct focus onto retinas, fixing near and far sight. | null | phy_0874 | concept | en | Why glasses? | [
"Extra lenses correct focus onto retinas, fixing near and far sight.",
"So the answer stands: Extra lenses correct focus onto retinas, fixing near and far sight."
] | physics | Answer: Extra lenses correct focus onto retinas, fixing near and far sight.
Steps:
1. Extra lenses correct focus onto retinas, fixing near and far sight.
2. So the answer stands: Extra lenses correct focus onto retinas, fixing near and far sight. | optics |
Period is 0.1 s. | {
"A": "0.09 s",
"B": "0.1 s",
"C": "0.08 s",
"D": "0.11 s"
} | phy_0875 | multiple_choice | en | A wave has frequency 10 Hz. What is its period? | [
"T = 1 / 10 Hz.",
"T = 0.1 s.",
"Select option B."
] | physics | Answer: 0.1 s
Steps:
1. T = 1 / 10 Hz.
2. T = 0.1 s.
3. Select option B.
Answer: (B) | waves |
Count: 36. | {
"A": "35",
"B": "37",
"C": "38",
"D": "36"
} | phy_0876 | multiple_choice | en | An atom is excited to level n = 9. How many spectral lines can it emit? | [
"Pairs: 9×8/2.",
"Lines: 36.",
"Select option D."
] | physics | Answer: 36
Steps:
1. Pairs: 9×8/2.
2. Lines: 36.
3. Select option D.
Answer: (D) | modern |
Kinetic energy is 144 J. | {
"A": "132 J",
"B": "156 J",
"C": "144 J",
"D": "168 J"
} | phy_0877 | multiple_choice | en | A 2 kg ball moves at 12 m/s. What is its kinetic energy? | [
"KE = ½×2 kg×(12 m/s)².",
"KE = 144 J.",
"Select option C."
] | physics | Answer: 144 J
Steps:
1. KE = ½×2 kg×(12 m/s)².
2. KE = 144 J.
3. Select option C.
Answer: (C) | mechanics |
Energy: 2000 J. | null | phy_0878 | worked_example | en | A 100 W heater runs for 20 s. Compute the energy used. | [
"E = P×t.",
"E = 100 W × 20 s.",
"= 2000 J."
] | physics | Answer: Energy: 2000 J.
Steps:
1. E = P×t.
2. E = 100 W × 20 s.
3. = 2000 J. | electromagnetism |
Teplota: 292 K. | null | phy_0879 | worked_example | cs | Teplota je 19 °C. Převeď ji na kelviny. | [
"Přičti 273.",
"19 + 273.",
"= 292 K."
] | physics | Answer: Teplota: 292 K.
Steps:
1. Přičti 273.
2. 19 + 273.
3. = 292 K. | thermodynamics |
Apparent depth: 170 cm. | null | phy_0880 | worked_example | en | An object sits 255 cm deep in glass (n = 1.5). Compute the apparent depth. | [
"d' = d/n.",
"d' = 255 cm / 1.5.",
"= 170 cm."
] | physics | Answer: Apparent depth: 170 cm.
Steps:
1. d' = d/n.
2. d' = 255 cm / 1.5.
3. = 170 cm. | optics |
Light ejects electrons only above threshold frequency, proving photons. | null | phy_0881 | concept | en | What does the photoelectric effect prove? | [
"Light ejects electrons only above threshold frequency, proving photons.",
"So the answer stands: Light ejects electrons only above threshold frequency, proving photons."
] | physics | Answer: Light ejects electrons only above threshold frequency, proving photons.
Steps:
1. Light ejects electrons only above threshold frequency, proving photons.
2. So the answer stands: Light ejects electrons only above threshold frequency, proving photons. | waves |
Mass number: 39. | null | phy_0882 | worked_example | en | A nucleus has 19 protons and 20 neutrons. Compute its mass number. | [
"A = Z+N.",
"A = 19 + 20.",
"= 39."
] | physics | Answer: Mass number: 39.
Steps:
1. A = Z+N.
2. A = 19 + 20.
3. = 39. | modern |
Výsledná síla: 14 N. | null | phy_0883 | worked_example | cs | Těleso 7 kg zrychluje 2 m/s². Spočítej výslednou sílu. | [
"F = m×a.",
"F = 7 kg × 2 m/s².",
"= 14 N."
] | physics | Answer: Výsledná síla: 14 N.
Steps:
1. F = m×a.
2. F = 7 kg × 2 m/s².
3. = 14 N. | mechanics |
Power: 867 W. | null | phy_0884 | worked_example | en | A current of 17 A flows through 3 Ω. Compute the dissipated power. | [
"P = I²×R.",
"P = (17 A)² × 3 Ω.",
"= 867 W."
] | physics | Answer: Power: 867 W.
Steps:
1. P = I²×R.
2. P = (17 A)² × 3 Ω.
3. = 867 W. | electromagnetism |
They map solid-liquid-gas borders versus temperature and pressure. | null | phy_0885 | concept | en | Why phase diagrams? | [
"They map solid-liquid-gas borders versus temperature and pressure.",
"So the answer stands: They map solid-liquid-gas borders versus temperature and pressure."
] | physics | Answer: They map solid-liquid-gas borders versus temperature and pressure.
Steps:
1. They map solid-liquid-gas borders versus temperature and pressure.
2. So the answer stands: They map solid-liquid-gas borders versus temperature and pressure. | thermodynamics |
Time is 10 s. | {
"A": "11 s",
"B": "12 s",
"C": "10 s",
"D": "9 s"
} | phy_0886 | multiple_choice | en | Light travels 30×10⁸ m. How many seconds does it take? (c = 3×10⁸ m/s) | [
"t = 30×10⁸ m / 3×10⁸ m/s.",
"t = 10 s.",
"Select option C."
] | physics | Answer: 10 s
Steps:
1. t = 30×10⁸ m / 3×10⁸ m/s.
2. t = 10 s.
3. Select option C.
Answer: (C) | optics |
3rd harmonic: 750 Hz. | null | phy_0887 | worked_example | en | A string's fundamental is 250 Hz. Compute its 3rd harmonic. | [
"f3 = 3×f1.",
"f3 = 3 × 250 Hz.",
"= 750 Hz."
] | physics | Answer: 3rd harmonic: 750 Hz.
Steps:
1. f3 = 3×f1.
2. f3 = 3 × 250 Hz.
3. = 750 Hz. | waves |
Fields jitter even empty, possibly driving cosmic speedup. | null | phy_0888 | concept | en | Why vacuum energy? | [
"Fields jitter even empty, possibly driving cosmic speedup.",
"So the answer stands: Fields jitter even empty, possibly driving cosmic speedup."
] | physics | Answer: Fields jitter even empty, possibly driving cosmic speedup.
Steps:
1. Fields jitter even empty, possibly driving cosmic speedup.
2. So the answer stands: Fields jitter even empty, possibly driving cosmic speedup. | modern |
Work: 340 J. | null | phy_0889 | worked_example | en | A force of 85 N pushes 4 m. Compute the work done. | [
"W = F×d.",
"W = 85 N × 4 m.",
"= 340 J."
] | physics | Answer: Work: 340 J.
Steps:
1. W = F×d.
2. W = 85 N × 4 m.
3. = 340 J. | mechanics |
Voltage is 50 V. | {
"A": "50 V",
"B": "45 V",
"C": "55 V",
"D": "60 V"
} | phy_0890 | multiple_choice | en | A current of 10 A flows through 5 Ω. What is the voltage? | [
"V = 10 A × 5 Ω.",
"V = 50 V.",
"Select option A."
] | physics | Answer: 50 V
Steps:
1. V = 10 A × 5 Ω.
2. V = 50 V.
3. Select option A.
Answer: (A) | electromagnetism |
Heat: 133952 J. | null | phy_0891 | worked_example | en | How much heat warms 2 kg of water by 16 K? (c = 4186 J/(kg·K)) | [
"Q = 2 kg × 4186 J/(kg·K) × 16 K.",
"= 133952 J."
] | physics | Answer: Heat: 133952 J.
Steps:
1. Q = 2 kg × 4186 J/(kg·K) × 16 K.
2. = 133952 J. | thermodynamics |
Magnification: 18×. | null | phy_0892 | worked_example | en | An image forms 180 cm from a lens, object at 10 cm. Compute the magnification. | [
"M = di/do.",
"M = 180 cm / 10 cm.",
"= 18×."
] | physics | Answer: Magnification: 18×.
Steps:
1. M = di/do.
2. M = 180 cm / 10 cm.
3. = 18×. | optics |
Vzdálenost: 1700 m. | null | phy_0893 | worked_example | cs | Hrom je slyšet 5 s po blesku. Jak daleko je bouře? (v = 340 m/s) | [
"d = v×t.",
"d = 340 m/s × 5 s.",
"= 1700 m."
] | physics | Answer: Vzdálenost: 1700 m.
Steps:
1. d = v×t.
2. d = 340 m/s × 5 s.
3. = 1700 m. | waves |
Survivors: 3600. | null | phy_0894 | worked_example | en | A sample of 14400 atoms undergoes 2 half-lives. Compute the survivors. | [
"Halve: 14400 → 7200.",
"Halve: 7200 → 3600.",
"= 3600."
] | physics | Answer: Survivors: 3600.
Steps:
1. Halve: 14400 → 7200.
2. Halve: 7200 → 3600.
3. = 3600. | modern |
Net force is 33 N. | {
"A": "30 N",
"B": "33 N",
"C": "36 N",
"D": "39 N"
} | phy_0895 | multiple_choice | en | A mass of 11 kg accelerates at 3 m/s². What is the net force? | [
"F = 11 kg × 3 m/s².",
"F = 33 N.",
"Select option B."
] | physics | Answer: 33 N
Steps:
1. F = 11 kg × 3 m/s².
2. F = 33 N.
3. Select option B.
Answer: (B) | mechanics |
Sériové rezistory sdílejí proud, napětí se skládají. | null | phy_0896 | concept | cs | Proč sériově sčítat? | [
"Sériové rezistory sdílejí proud, napětí se skládají.",
"Odpověď tedy platí: Sériové rezistory sdílejí proud, napětí se skládají."
] | physics | Answer: Sériové rezistory sdílejí proud, napětí se skládají.
Steps:
1. Sériové rezistory sdílejí proud, napětí se skládají.
2. Odpověď tedy platí: Sériové rezistory sdílejí proud, napětí se skládají. | electromagnetism |
Heat needed is 41860 J. | {
"A": "37674 J",
"B": "41860 J",
"C": "46046 J",
"D": "50232 J"
} | phy_0897 | multiple_choice | en | How much heat warms 1 kg of water by 10 K? (c = 4186 J/(kg·K)) | [
"Q = 1 kg × 4186 J/(kg·K) × 10 K.",
"Q = 41860 J.",
"Select option B."
] | physics | Answer: 41860 J
Steps:
1. Q = 1 kg × 4186 J/(kg·K) × 10 K.
2. Q = 41860 J.
3. Select option B.
Answer: (B) | thermodynamics |
Three cone types mix red, green, blue signals into all hues. | null | phy_0898 | concept | en | What is colour vision? | [
"Three cone types mix red, green, blue signals into all hues.",
"So the answer stands: Three cone types mix red, green, blue signals into all hues."
] | physics | Answer: Three cone types mix red, green, blue signals into all hues.
Steps:
1. Three cone types mix red, green, blue signals into all hues.
2. So the answer stands: Three cone types mix red, green, blue signals into all hues. | optics |
Odražené vlny se zamykají do uzlů. | null | phy_0899 | concept | cs | Proč stojaté vlnění? | [
"Odražené vlny se zamykají do uzlů.",
"Odpověď tedy platí: Odražené vlny se zamykají do uzlů."
] | physics | Answer: Odražené vlny se zamykají do uzlů.
Steps:
1. Odražené vlny se zamykají do uzlů.
2. Odpověď tedy platí: Odražené vlny se zamykají do uzlů. | waves |
Lines: 210. | null | phy_0900 | worked_example | en | An atom is excited to level n = 21. Count the spectral lines it can emit. | [
"Pairs: 21×20/2.",
"= 420/2.",
"= 210."
] | physics | Answer: Lines: 210.
Steps:
1. Pairs: 21×20/2.
2. = 420/2.
3. = 210. | modern |
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