answer string | choices dict | id string | kind string | lang string | question string | steps list | subject string | text string | topic string |
|---|---|---|---|---|---|---|---|---|---|
Efficiency is 30%. | {
"A": "20%",
"B": "40%",
"C": "50%",
"D": "30%"
} | phy_0201 | multiple_choice | en | An engine turns 300 J of 1000 J heat into work. What is its efficiency? | [
"300 J / 1000 J.",
"= 30%.",
"Select option D."
] | physics | Answer: 30%
Steps:
1. 300 J / 1000 J.
2. = 30%.
3. Select option D.
Answer: (D) | thermodynamics |
Diverging rays seem to meet behind mirrors, so eyes see unreachable pictures. | null | phy_0202 | concept | en | Why virtual images? | [
"Diverging rays seem to meet behind mirrors, so eyes see unreachable pictures.",
"So the answer stands: Diverging rays seem to meet behind mirrors, so eyes see unreachable pictures."
] | physics | Answer: Diverging rays seem to meet behind mirrors, so eyes see unreachable pictures.
Steps:
1. Diverging rays seem to meet behind mirrors, so eyes see unreachable pictures.
2. So the answer stands: Diverging rays seem to meet behind mirrors, so eyes see unreachable pictures. | optics |
Peak displacement from rest, setting loudness and brightness. | null | phy_0203 | concept | en | What is amplitude? | [
"Peak displacement from rest, setting loudness and brightness.",
"So the answer stands: Peak displacement from rest, setting loudness and brightness."
] | physics | Answer: Peak displacement from rest, setting loudness and brightness.
Steps:
1. Peak displacement from rest, setting loudness and brightness.
2. So the answer stands: Peak displacement from rest, setting loudness and brightness. | waves |
Unseen mass bends galaxies more than visible stuff allows. | null | phy_0204 | concept | en | What is dark matter? | [
"Unseen mass bends galaxies more than visible stuff allows.",
"So the answer stands: Unseen mass bends galaxies more than visible stuff allows."
] | physics | Answer: Unseen mass bends galaxies more than visible stuff allows.
Steps:
1. Unseen mass bends galaxies more than visible stuff allows.
2. So the answer stands: Unseen mass bends galaxies more than visible stuff allows. | modern |
Work: 100 J. | null | phy_0205 | worked_example | en | A force of 25 N pushes 4 m. Compute the work done. | [
"W = F×d.",
"W = 25 N × 4 m.",
"= 100 J."
] | physics | Answer: Work: 100 J.
Steps:
1. W = F×d.
2. W = 25 N × 4 m.
3. = 100 J. | mechanics |
Příkon je 36 W. | {
"A": "24 W",
"B": "36 W",
"C": "48 W",
"D": "60 W"
} | phy_0206 | multiple_choice | cs | Žárovka běží na 12 V a bere 3 A. Jaký je její příkon? | [
"P = 12 V × 3 A.",
"P = 36 W.",
"Vyber možnost B."
] | physics | Answer: 36 W
Steps:
1. P = 12 V × 3 A.
2. P = 36 W.
3. Vyber možnost B.
Answer: (B) | electromagnetism |
Temperature: 292 K. | null | phy_0207 | worked_example | en | Temperature is 19 °C. Convert it to kelvin. | [
"Add 273.",
"19 + 273.",
"= 292 K."
] | physics | Answer: Temperature: 292 K.
Steps:
1. Add 273.
2. 19 + 273.
3. = 292 K. | thermodynamics |
Apparent depth: 50 cm. | null | phy_0208 | worked_example | en | An object sits 75 cm deep in glass (n = 1.5). Compute the apparent depth. | [
"d' = d/n.",
"d' = 75 cm / 1.5.",
"= 50 cm."
] | physics | Answer: Apparent depth: 50 cm.
Steps:
1. d' = d/n.
2. d' = 75 cm / 1.5.
3. = 50 cm. | optics |
It is seconds per cycle, the inverse of frequency always. | null | phy_0209 | concept | en | Why period? | [
"It is seconds per cycle, the inverse of frequency always.",
"So the answer stands: It is seconds per cycle, the inverse of frequency always."
] | physics | Answer: It is seconds per cycle, the inverse of frequency always.
Steps:
1. It is seconds per cycle, the inverse of frequency always.
2. So the answer stands: It is seconds per cycle, the inverse of frequency always. | waves |
Expansion accelerates as if vacuum pushes space apart. | null | phy_0210 | concept | en | Why dark energy? | [
"Expansion accelerates as if vacuum pushes space apart.",
"So the answer stands: Expansion accelerates as if vacuum pushes space apart."
] | physics | Answer: Expansion accelerates as if vacuum pushes space apart.
Steps:
1. Expansion accelerates as if vacuum pushes space apart.
2. So the answer stands: Expansion accelerates as if vacuum pushes space apart. | modern |
Momentum: 24 kg·m/s. | null | phy_0211 | worked_example | en | A mass of 8 kg moves at 3 m/s. Compute its momentum. | [
"p = m×v.",
"p = 8 kg × 3 m/s.",
"= 24 kg·m/s."
] | physics | Answer: Momentum: 24 kg·m/s.
Steps:
1. p = m×v.
2. p = 8 kg × 3 m/s.
3. = 24 kg·m/s. | mechanics |
Charge is 60 C. | {
"A": "40 C",
"B": "80 C",
"C": "100 C",
"D": "60 C"
} | phy_0212 | multiple_choice | en | A current of 4 A flows for 15 s. How much charge passes? | [
"Q = 4 A × 15 s.",
"Q = 60 C.",
"Select option D."
] | physics | Answer: 60 C
Steps:
1. Q = 4 A × 15 s.
2. Q = 60 C.
3. Select option D.
Answer: (D) | electromagnetism |
The answer is Kelvin scale. | {
"A": "Kelvin scale",
"B": "Celsius scale",
"C": "Beaufort scale",
"D": "Richter scale"
} | phy_0213 | multiple_choice | en | Choose: what starts at zero motion? | [
"Absolute zero based.",
"So: Kelvin scale.",
"Select option A."
] | physics | Answer: Kelvin scale
Steps:
1. Absolute zero based.
2. So: Kelvin scale.
3. Select option A.
Answer: (A) | thermodynamics |
The answer is Diffraction. | {
"A": "Reflection",
"B": "Diffraction",
"C": "Absorption",
"D": "Emission"
} | phy_0214 | multiple_choice | en | Choose: what proves waves? | [
"Edges fringed.",
"So: Diffraction.",
"Select option B."
] | physics | Answer: Diffraction
Steps:
1. Edges fringed.
2. So: Diffraction.
3. Select option B.
Answer: (B) | optics |
3. harmonická je 330 Hz. | {
"A": "300 Hz",
"B": "360 Hz",
"C": "330 Hz",
"D": "390 Hz"
} | phy_0215 | multiple_choice | cs | Základ struny je 110 Hz. Jaká je její 3. harmonická? | [
"f3 = 3 × 110 Hz.",
"f3 = 330 Hz.",
"Vyber možnost C."
] | physics | Answer: 330 Hz
Steps:
1. f3 = 3 × 110 Hz.
2. f3 = 330 Hz.
3. Vyber možnost C.
Answer: (C) | waves |
Count: 6. | {
"A": "5",
"B": "7",
"C": "6",
"D": "8"
} | phy_0216 | multiple_choice | en | An atom is excited to level n = 4. How many spectral lines can it emit? | [
"Pairs: 4×3/2.",
"Lines: 6.",
"Select option C."
] | physics | Answer: 6
Steps:
1. Pairs: 4×3/2.
2. Lines: 6.
3. Select option C.
Answer: (C) | modern |
Friction opposes sliding between surfaces, converting motion energy into heat. | null | phy_0217 | concept | en | What is friction? | [
"Friction opposes sliding between surfaces, converting motion energy into heat.",
"So the answer stands: Friction opposes sliding between surfaces, converting motion energy into heat."
] | physics | Answer: Friction opposes sliding between surfaces, converting motion energy into heat.
Steps:
1. Friction opposes sliding between surfaces, converting motion energy into heat.
2. So the answer stands: Friction opposes sliding between surfaces, converting motion energy into heat. | mechanics |
The answer is Voltage. | {
"A": "Voltage",
"B": "Current",
"C": "Power",
"D": "Force"
} | phy_0218 | multiple_choice | en | Choose: what is energy per charge? | [
"Volts push flow.",
"So: Voltage.",
"Select option A."
] | physics | Answer: Voltage
Steps:
1. Volts push flow.
2. So: Voltage.
3. Select option A.
Answer: (A) | electromagnetism |
Heat: 41860 J. | null | phy_0219 | worked_example | en | How much heat warms 2 kg of water by 5 K? (c = 4186 J/(kg·K)) | [
"Q = 2 kg × 4186 J/(kg·K) × 5 K.",
"= 41860 J."
] | physics | Answer: Heat: 41860 J.
Steps:
1. Q = 2 kg × 4186 J/(kg·K) × 5 K.
2. = 41860 J. | thermodynamics |
Magnification: 6×. | null | phy_0220 | worked_example | en | An image forms 60 cm from a lens, object at 10 cm. Compute the magnification. | [
"M = di/do.",
"M = 60 cm / 10 cm.",
"= 6×."
] | physics | Answer: Magnification: 6×.
Steps:
1. M = di/do.
2. M = 60 cm / 10 cm.
3. = 6×. | optics |
Distance: 2040 m. | null | phy_0221 | worked_example | en | Thunder is heard 6 s after lightning. How far away is the storm? (v = 340 m/s) | [
"d = v×t.",
"d = 340 m/s × 6 s.",
"= 2040 m."
] | physics | Answer: Distance: 2040 m.
Steps:
1. d = v×t.
2. d = 340 m/s × 6 s.
3. = 2040 m. | waves |
Lines: 21. | null | phy_0222 | worked_example | en | An atom is excited to level n = 7. Count the spectral lines it can emit. | [
"Pairs: 7×6/2.",
"= 42/2.",
"= 21."
] | physics | Answer: Lines: 21.
Steps:
1. Pairs: 7×6/2.
2. = 42/2.
3. = 21. | modern |
The answer is Work. | {
"A": "Power",
"B": "Work",
"C": "Torque",
"D": "Impulse"
} | phy_0223 | multiple_choice | en | Choose: what is force times distance? | [
"Joules counted.",
"So: Work.",
"Select option B."
] | physics | Answer: Work
Steps:
1. Joules counted.
2. So: Work.
3. Select option B.
Answer: (B) | mechanics |
Power: 108 W. | null | phy_0224 | worked_example | en | A current of 6 A flows through 3 Ω. Compute the dissipated power. | [
"P = I²×R.",
"P = (6 A)² × 3 Ω.",
"= 108 W."
] | physics | Answer: Power: 108 W.
Steps:
1. P = I²×R.
2. P = (6 A)² × 3 Ω.
3. = 108 W. | electromagnetism |
The answer is Carnot limit. | {
"A": "Speed limit",
"B": "Carnot limit",
"C": "Weight limit",
"D": "Age limit"
} | phy_0225 | multiple_choice | en | Choose: what caps all engines? | [
"Temps ratio bound.",
"So: Carnot limit.",
"Select option B."
] | physics | Answer: Carnot limit
Steps:
1. Temps ratio bound.
2. So: Carnot limit.
3. Select option B.
Answer: (B) | thermodynamics |
Glass bends colours differently, splitting white into rainbows. | null | phy_0226 | concept | en | What is dispersion? | [
"Glass bends colours differently, splitting white into rainbows.",
"So the answer stands: Glass bends colours differently, splitting white into rainbows."
] | physics | Answer: Glass bends colours differently, splitting white into rainbows.
Steps:
1. Glass bends colours differently, splitting white into rainbows.
2. So the answer stands: Glass bends colours differently, splitting white into rainbows. | optics |
3rd harmonic is 360 Hz. | {
"A": "330 Hz",
"B": "390 Hz",
"C": "420 Hz",
"D": "360 Hz"
} | phy_0227 | multiple_choice | en | A string's fundamental is 120 Hz. What is its 3rd harmonic? | [
"f3 = 3 × 120 Hz.",
"f3 = 360 Hz.",
"Select option D."
] | physics | Answer: 360 Hz
Steps:
1. f3 = 3 × 120 Hz.
2. f3 = 360 Hz.
3. Select option D.
Answer: (D) | waves |
Zbude 100 atomů. | {
"A": "100",
"B": "50",
"C": "150",
"D": "200"
} | phy_0228 | multiple_choice | cs | Vzorek 400 atomů projde 2 poločasy. Kolik atomů zbude? | [
"Půlit dvakrát: 400 → 200 → 100.",
"Zbývá: 100.",
"Vyber možnost A."
] | physics | Answer: 100
Steps:
1. Půlit dvakrát: 400 → 200 → 100.
2. Zbývá: 100.
3. Vyber možnost A.
Answer: (A) | modern |
They isolate one body with all force arrows, making Newton's laws easy to apply. | null | phy_0229 | concept | en | Why use free-body diagrams? | [
"They isolate one body with all force arrows, making Newton's laws easy to apply.",
"So the answer stands: They isolate one body with all force arrows, making Newton's laws easy to apply."
] | physics | Answer: They isolate one body with all force arrows, making Newton's laws easy to apply.
Steps:
1. They isolate one body with all force arrows, making Newton's laws easy to apply.
2. So the answer stands: They isolate one body with all force arrows, making Newton's laws easy to apply. | mechanics |
Náboj je 40 C. | {
"A": "20 C",
"B": "60 C",
"C": "40 C",
"D": "80 C"
} | phy_0230 | multiple_choice | cs | Proud 4 A teče po 10 s. Kolik náboje projde? | [
"Q = 4 A × 10 s.",
"Q = 40 C.",
"Vyber možnost C."
] | physics | Answer: 40 C
Steps:
1. Q = 4 A × 10 s.
2. Q = 40 C.
3. Vyber možnost C.
Answer: (C) | electromagnetism |
Teplo je 8372 J. | {
"A": "4186 J",
"B": "8372 J",
"C": "12558 J",
"D": "16744 J"
} | phy_0231 | multiple_choice | cs | Kolik tepla ohřeje 1 kg vody o 2 K? (c = 4186 J/(kg·K)) | [
"Q = 1 kg × 4186 J/(kg·K) × 2 K.",
"Q = 8372 J.",
"Vyber možnost B."
] | physics | Answer: 8372 J
Steps:
1. Q = 1 kg × 4186 J/(kg·K) × 2 K.
2. Q = 8372 J.
3. Vyber možnost B.
Answer: (B) | thermodynamics |
Zvětšení: 4×. | null | phy_0232 | worked_example | cs | Obraz vzniká 40 cm od čočky, předmět v 10 cm. Spočítej zvětšení. | [
"M = di/do.",
"M = 40 cm / 10 cm.",
"= 4×."
] | physics | Answer: Zvětšení: 4×.
Steps:
1. M = di/do.
2. M = 40 cm / 10 cm.
3. = 4×. | optics |
Odpověď je vlna. | {
"A": "vítr",
"B": "řeka",
"C": "nákladní auto",
"D": "vlna"
} | phy_0233 | multiple_choice | cs | Vyber: co nese bez látky? | [
"Energie cestuje.",
"Tedy: vlna.",
"Vyber možnost D."
] | physics | Answer: vlna
Steps:
1. Energie cestuje.
2. Tedy: vlna.
3. Vyber možnost D.
Answer: (D) | waves |
Mass number is 6. | {
"A": "5",
"B": "7",
"C": "8",
"D": "6"
} | phy_0234 | multiple_choice | en | A nucleus has 3 protons and 3 neutrons. What is its mass number? | [
"A = 3 + 3.",
"A = 6.",
"Select option D."
] | physics | Answer: 6
Steps:
1. A = 3 + 3.
2. A = 6.
3. Select option D.
Answer: (D) | modern |
Weight is gravity's pull mg on mass, so it changes with planet while mass stays fixed. | null | phy_0235 | concept | en | What is weight? | [
"Weight is gravity's pull mg on mass, so it changes with planet while mass stays fixed.",
"So the answer stands: Weight is gravity's pull mg on mass, so it changes with planet while mass stays fixed."
] | physics | Answer: Weight is gravity's pull mg on mass, so it changes with planet while mass stays fixed.
Steps:
1. Weight is gravity's pull mg on mass, so it changes with planet while mass stays fixed.
2. So the answer stands: Weight is gravity's pull mg on mass, so it changes with planet while mass stays fixed. | mechanics |
Voltage: 72 V. | null | phy_0236 | worked_example | en | A current of 6 A flows through 12 Ω. Compute the voltage. | [
"V = I×R.",
"V = 6 A × 12 Ω.",
"= 72 V."
] | physics | Answer: Voltage: 72 V.
Steps:
1. V = I×R.
2. V = 6 A × 12 Ω.
3. = 72 V. | electromagnetism |
Temperature is 295 K. | {
"A": "294 K",
"B": "296 K",
"C": "295 K",
"D": "297 K"
} | phy_0237 | multiple_choice | en | Room temperature is 22 °C. What is it in kelvin? | [
"22 °C + 273.",
"= 295 K.",
"Select option C."
] | physics | Answer: 295 K
Steps:
1. 22 °C + 273.
2. = 295 K.
3. Select option C.
Answer: (C) | thermodynamics |
Magnification is 4×. | {
"A": "3×",
"B": "5×",
"C": "4×",
"D": "6×"
} | phy_0238 | multiple_choice | en | An image forms 40 cm from a lens, object at 10 cm. What is the magnification? | [
"M = 40 cm / 10 cm.",
"M = 4×.",
"Select option C."
] | physics | Answer: 4×
Steps:
1. M = 40 cm / 10 cm.
2. M = 4×.
3. Select option C.
Answer: (C) | optics |
The answer is v equals fλ. | {
"A": "v equals fλ",
"B": "E equals mc",
"C": "F equals ma",
"D": "pV equals nRT"
} | phy_0239 | multiple_choice | en | Choose: what links speed, cycles? | [
"Master relation held.",
"So: v equals fλ.",
"Select option A."
] | physics | Answer: v equals fλ
Steps:
1. Master relation held.
2. So: v equals fλ.
3. Select option A.
Answer: (A) | waves |
Tiny scales follow wave rules with discrete outcomes and uncertainty. | null | phy_0240 | concept | en | What is quantum mechanics? | [
"Tiny scales follow wave rules with discrete outcomes and uncertainty.",
"So the answer stands: Tiny scales follow wave rules with discrete outcomes and uncertainty."
] | physics | Answer: Tiny scales follow wave rules with discrete outcomes and uncertainty.
Steps:
1. Tiny scales follow wave rules with discrete outcomes and uncertainty.
2. So the answer stands: Tiny scales follow wave rules with discrete outcomes and uncertainty. | modern |
Net force is 12 N. | {
"A": "9 N",
"B": "15 N",
"C": "12 N",
"D": "18 N"
} | phy_0241 | multiple_choice | en | A mass of 4 kg accelerates at 3 m/s². What is the net force? | [
"F = 4 kg × 3 m/s².",
"F = 12 N.",
"Select option C."
] | physics | Answer: 12 N
Steps:
1. F = 4 kg × 3 m/s².
2. F = 12 N.
3. Select option C.
Answer: (C) | mechanics |
Energy: 1000 J. | null | phy_0242 | worked_example | en | A 100 W heater runs for 10 s. Compute the energy used. | [
"E = P×t.",
"E = 100 W × 10 s.",
"= 1000 J."
] | physics | Answer: Energy: 1000 J.
Steps:
1. E = P×t.
2. E = 100 W × 10 s.
3. = 1000 J. | electromagnetism |
Účinnost je 20 %. | {
"A": "10 %",
"B": "30 %",
"C": "20 %",
"D": "40 %"
} | phy_0243 | multiple_choice | cs | Motor mění 200 J z 1000 J tepla v práci. Jaká je jeho účinnost? | [
"200 J / 1000 J.",
"= 20 %.",
"Vyber možnost C."
] | physics | Answer: 20 %
Steps:
1. 200 J / 1000 J.
2. = 20 %.
3. Vyber možnost C.
Answer: (C) | thermodynamics |
Time: 4.3 s. | null | phy_0244 | worked_example | en | Light travels 13×10⁸ m. Compute the travel time. (c = 3×10⁸ m/s) | [
"t = d/c.",
"t = 13×10⁸ / 3×10⁸ s.",
"= 4.3 s."
] | physics | Answer: Time: 4.3 s.
Steps:
1. t = d/c.
2. t = 13×10⁸ / 3×10⁸ s.
3. = 4.3 s. | optics |
Odpověď je harmonické. | {
"A": "harmonické",
"B": "statiky",
"C": "hluky",
"D": "ticha"
} | phy_0245 | multiple_choice | cs | Vyber: co barví témbr? | [
"Svrchní přidány.",
"Tedy: harmonické.",
"Vyber možnost A."
] | physics | Answer: harmonické
Steps:
1. Svrchní přidány.
2. Tedy: harmonické.
3. Vyber možnost A.
Answer: (A) | waves |
The answer is Moving clocks. | {
"A": "Moving clocks",
"B": "Broken watches",
"C": "Stopped timers",
"D": "Lost phones"
} | phy_0246 | multiple_choice | en | Choose: what ticks slower? | [
"Muons confirm.",
"So: Moving clocks.",
"Select option A."
] | physics | Answer: Moving clocks
Steps:
1. Muons confirm.
2. So: Moving clocks.
3. Select option A.
Answer: (A) | modern |
Net force: 14 N. | null | phy_0247 | worked_example | en | A mass of 7 kg accelerates at 2 m/s². Compute the net force. | [
"F = m×a.",
"F = 7 kg × 2 m/s².",
"= 14 N."
] | physics | Answer: Net force: 14 N.
Steps:
1. F = m×a.
2. F = 7 kg × 2 m/s².
3. = 14 N. | mechanics |
Síla škáluje s náboji a druhou mocninou vzdálenosti. | null | phy_0248 | concept | cs | Proč Coulombův zákon? | [
"Síla škáluje s náboji a druhou mocninou vzdálenosti.",
"Odpověď tedy platí: Síla škáluje s náboji a druhou mocninou vzdálenosti."
] | physics | Answer: Síla škáluje s náboji a druhou mocninou vzdálenosti.
Steps:
1. Síla škáluje s náboji a druhou mocninou vzdálenosti.
2. Odpověď tedy platí: Síla škáluje s náboji a druhou mocninou vzdálenosti. | electromagnetism |
Heat needed is 16744 J. | {
"A": "12558 J",
"B": "20930 J",
"C": "25116 J",
"D": "16744 J"
} | phy_0249 | multiple_choice | en | How much heat warms 1 kg of water by 4 K? (c = 4186 J/(kg·K)) | [
"Q = 1 kg × 4186 J/(kg·K) × 4 K.",
"Q = 16744 J.",
"Select option D."
] | physics | Answer: 16744 J
Steps:
1. Q = 1 kg × 4186 J/(kg·K) × 4 K.
2. Q = 16744 J.
3. Select option D.
Answer: (D) | thermodynamics |
Drops refract, reflect, and disperse sunlight at 42 degrees to watchers. | null | phy_0250 | concept | en | Why rainbows? | [
"Drops refract, reflect, and disperse sunlight at 42 degrees to watchers.",
"So the answer stands: Drops refract, reflect, and disperse sunlight at 42 degrees to watchers."
] | physics | Answer: Drops refract, reflect, and disperse sunlight at 42 degrees to watchers.
Steps:
1. Drops refract, reflect, and disperse sunlight at 42 degrees to watchers.
2. So the answer stands: Drops refract, reflect, and disperse sunlight at 42 degrees to watchers. | optics |
3rd harmonic: 420 Hz. | null | phy_0251 | worked_example | en | A string's fundamental is 140 Hz. Compute its 3rd harmonic. | [
"f3 = 3×f1.",
"f3 = 3 × 140 Hz.",
"= 420 Hz."
] | physics | Answer: 3rd harmonic: 420 Hz.
Steps:
1. f3 = 3×f1.
2. f3 = 3 × 140 Hz.
3. = 420 Hz. | waves |
The answer is Fusion. | {
"A": "Confusion",
"B": "Fusion",
"C": "Diffusion",
"D": "Illusion"
} | phy_0252 | multiple_choice | en | Choose: what merges light? | [
"Stars lit.",
"So: Fusion.",
"Select option B."
] | physics | Answer: Fusion
Steps:
1. Stars lit.
2. So: Fusion.
3. Select option B.
Answer: (B) | modern |
Výsledná síla: 8 N. | null | phy_0253 | worked_example | cs | Těleso 4 kg zrychluje 2 m/s². Spočítej výslednou sílu. | [
"F = m×a.",
"F = 4 kg × 2 m/s².",
"= 8 N."
] | physics | Answer: Výsledná síla: 8 N.
Steps:
1. F = m×a.
2. F = 4 kg × 2 m/s².
3. = 8 N. | mechanics |
Series resistors share one current, so voltages stack across each in turn. | null | phy_0254 | concept | en | Why series adds? | [
"Series resistors share one current, so voltages stack across each in turn.",
"So the answer stands: Series resistors share one current, so voltages stack across each in turn."
] | physics | Answer: Series resistors share one current, so voltages stack across each in turn.
Steps:
1. Series resistors share one current, so voltages stack across each in turn.
2. So the answer stands: Series resistors share one current, so voltages stack across each in turn. | electromagnetism |
Entropy of isolated systems never falls, forcing heat toward uniform spread. | null | phy_0255 | concept | en | What is the second law? | [
"Entropy of isolated systems never falls, forcing heat toward uniform spread.",
"So the answer stands: Entropy of isolated systems never falls, forcing heat toward uniform spread."
] | physics | Answer: Entropy of isolated systems never falls, forcing heat toward uniform spread.
Steps:
1. Entropy of isolated systems never falls, forcing heat toward uniform spread.
2. So the answer stands: Entropy of isolated systems never falls, forcing heat toward uniform spread. | thermodynamics |
Waves bend around edges and slits, proving light's wave nature. | null | phy_0256 | concept | en | What is diffraction? | [
"Waves bend around edges and slits, proving light's wave nature.",
"So the answer stands: Waves bend around edges and slits, proving light's wave nature."
] | physics | Answer: Waves bend around edges and slits, proving light's wave nature.
Steps:
1. Waves bend around edges and slits, proving light's wave nature.
2. So the answer stands: Waves bend around edges and slits, proving light's wave nature. | optics |
The answer is Decibel. | {
"A": "Metre",
"B": "Decibel",
"C": "Second",
"D": "Gram"
} | phy_0257 | multiple_choice | en | Choose: what logs loudness? | [
"Power ratioed.",
"So: Decibel.",
"Select option B."
] | physics | Answer: Decibel
Steps:
1. Power ratioed.
2. So: Decibel.
3. Select option B.
Answer: (B) | waves |
Mass number: 13. | null | phy_0258 | worked_example | en | A nucleus has 6 protons and 7 neutrons. Compute its mass number. | [
"A = Z+N.",
"A = 6 + 7.",
"= 13."
] | physics | Answer: Mass number: 13.
Steps:
1. A = Z+N.
2. A = 6 + 7.
3. = 13. | modern |
Earth's mass and radius set surface gravity near 9.8 m/s², weaker on the Moon. | null | phy_0259 | concept | en | Why g is 9.8? | [
"Earth's mass and radius set surface gravity near 9.8 m/s², weaker on the Moon.",
"So the answer stands: Earth's mass and radius set surface gravity near 9.8 m/s², weaker on the Moon."
] | physics | Answer: Earth's mass and radius set surface gravity near 9.8 m/s², weaker on the Moon.
Steps:
1. Earth's mass and radius set surface gravity near 9.8 m/s², weaker on the Moon.
2. So the answer stands: Earth's mass and radius set surface gravity near 9.8 m/s², weaker on the Moon. | mechanics |
Parallel branches share voltage while splitting current, keeping bulbs bright. | null | phy_0260 | concept | en | What is parallel for? | [
"Parallel branches share voltage while splitting current, keeping bulbs bright.",
"So the answer stands: Parallel branches share voltage while splitting current, keeping bulbs bright."
] | physics | Answer: Parallel branches share voltage while splitting current, keeping bulbs bright.
Steps:
1. Parallel branches share voltage while splitting current, keeping bulbs bright.
2. So the answer stands: Parallel branches share voltage while splitting current, keeping bulbs bright. | electromagnetism |
Power: 90 W. | null | phy_0261 | worked_example | en | An engine does 900 J of work in 10 s. Compute its power. | [
"P = W/t.",
"P = 900 J / 10 s.",
"= 90 W."
] | physics | Answer: Power: 90 W.
Steps:
1. P = W/t.
2. P = 900 J / 10 s.
3. = 90 W. | thermodynamics |
Time is 3 s. | {
"A": "4 s",
"B": "5 s",
"C": "2 s",
"D": "3 s"
} | phy_0262 | multiple_choice | en | Light travels 9×10⁸ m. How many seconds does it take? (c = 3×10⁸ m/s) | [
"t = 9×10⁸ m / 3×10⁸ m/s.",
"t = 3 s.",
"Select option D."
] | physics | Answer: 3 s
Steps:
1. t = 9×10⁸ m / 3×10⁸ m/s.
2. t = 3 s.
3. Select option D.
Answer: (D) | optics |
Speed is 400 m/s. | {
"A": "350 m/s",
"B": "450 m/s",
"C": "400 m/s",
"D": "500 m/s"
} | phy_0263 | multiple_choice | en | A string wave has f = 200 Hz and λ = 2 m. What is its speed? | [
"v = 200 Hz × 2 m.",
"v = 400 m/s.",
"Select option C."
] | physics | Answer: 400 m/s
Steps:
1. v = 200 Hz × 2 m.
2. v = 400 m/s.
3. Select option C.
Answer: (C) | waves |
Survivors: 1000. | null | phy_0264 | worked_example | en | A sample of 4000 atoms undergoes 2 half-lives. Compute the survivors. | [
"Halve: 4000 → 2000.",
"Halve: 2000 → 1000.",
"= 1000."
] | physics | Answer: Survivors: 1000.
Steps:
1. Halve: 4000 → 2000.
2. Halve: 2000 → 1000.
3. = 1000. | modern |
Práce: 60 J. | null | phy_0265 | worked_example | cs | Síla 15 N tlačí na dráze 4 m. Spočítej vykonanou práci. | [
"W = F×d.",
"W = 15 N × 4 m.",
"= 60 J."
] | physics | Answer: Práce: 60 J.
Steps:
1. W = F×d.
2. W = 15 N × 4 m.
3. = 60 J. | mechanics |
Charge and energy conservation force currents to balance and loops to sum zero. | null | phy_0266 | concept | en | Why Kirchhoff's rules? | [
"Charge and energy conservation force currents to balance and loops to sum zero.",
"So the answer stands: Charge and energy conservation force currents to balance and loops to sum zero."
] | physics | Answer: Charge and energy conservation force currents to balance and loops to sum zero.
Steps:
1. Charge and energy conservation force currents to balance and loops to sum zero.
2. So the answer stands: Charge and energy conservation force currents to balance and loops to sum zero. | electromagnetism |
Temperature: 293 K. | null | phy_0267 | worked_example | en | Temperature is 20 °C. Convert it to kelvin. | [
"Add 273.",
"20 + 273.",
"= 293 K."
] | physics | Answer: Temperature: 293 K.
Steps:
1. Add 273.
2. 20 + 273.
3. = 293 K. | thermodynamics |
Overlapping waves add or cancel by phase, painting fringes and colours. | null | phy_0268 | concept | en | Why interference? | [
"Overlapping waves add or cancel by phase, painting fringes and colours.",
"So the answer stands: Overlapping waves add or cancel by phase, painting fringes and colours."
] | physics | Answer: Overlapping waves add or cancel by phase, painting fringes and colours.
Steps:
1. Overlapping waves add or cancel by phase, painting fringes and colours.
2. So the answer stands: Overlapping waves add or cancel by phase, painting fringes and colours. | optics |
Speed: 1350 m/s. | null | phy_0269 | worked_example | en | A string wave has f = 450 Hz and λ = 3 m. Compute its speed. | [
"v = f×λ.",
"v = 450 Hz × 3 m.",
"= 1350 m/s."
] | physics | Answer: Speed: 1350 m/s.
Steps:
1. v = f×λ.
2. v = 450 Hz × 3 m.
3. = 1350 m/s. | waves |
Bound systems allow only ladder energies, painting spectral lines. | null | phy_0270 | concept | en | Why quantization? | [
"Bound systems allow only ladder energies, painting spectral lines.",
"So the answer stands: Bound systems allow only ladder energies, painting spectral lines."
] | physics | Answer: Bound systems allow only ladder energies, painting spectral lines.
Steps:
1. Bound systems allow only ladder energies, painting spectral lines.
2. So the answer stands: Bound systems allow only ladder energies, painting spectral lines. | modern |
Tíha je gravitační tah mg na hmotnost. | null | phy_0271 | concept | cs | Co je tíha? | [
"Tíha je gravitační tah mg na hmotnost.",
"Odpověď tedy platí: Tíha je gravitační tah mg na hmotnost."
] | physics | Answer: Tíha je gravitační tah mg na hmotnost.
Steps:
1. Tíha je gravitační tah mg na hmotnost.
2. Odpověď tedy platí: Tíha je gravitační tah mg na hmotnost. | mechanics |
Pole mapuje sílu na náboj prostorem. | null | phy_0272 | concept | cs | Co je elektrické pole? | [
"Pole mapuje sílu na náboj prostorem.",
"Odpověď tedy platí: Pole mapuje sílu na náboj prostorem."
] | physics | Answer: Pole mapuje sílu na náboj prostorem.
Steps:
1. Pole mapuje sílu na náboj prostorem.
2. Odpověď tedy platí: Pole mapuje sílu na náboj prostorem. | electromagnetism |
Efficiency is 40%. | {
"A": "40%",
"B": "30%",
"C": "50%",
"D": "60%"
} | phy_0273 | multiple_choice | en | An engine turns 400 J of 1000 J heat into work. What is its efficiency? | [
"400 J / 1000 J.",
"= 40%.",
"Select option A."
] | physics | Answer: 40%
Steps:
1. 400 J / 1000 J.
2. = 40%.
3. Select option A.
Answer: (A) | thermodynamics |
Apparent depth is 40 cm. | {
"A": "40 cm",
"B": "35 cm",
"C": "45 cm",
"D": "50 cm"
} | phy_0274 | multiple_choice | en | An object sits 60 cm deep in glass (n = 1.5). What is the apparent depth? | [
"d' = 60 cm / 1.5.",
"d' = 40 cm.",
"Select option A."
] | physics | Answer: 40 cm
Steps:
1. d' = 60 cm / 1.5.
2. d' = 40 cm.
3. Select option A.
Answer: (A) | optics |
Distance: 2380 m. | null | phy_0275 | worked_example | en | Thunder is heard 7 s after lightning. How far away is the storm? (v = 340 m/s) | [
"d = v×t.",
"d = 340 m/s × 7 s.",
"= 2380 m."
] | physics | Answer: Distance: 2380 m.
Steps:
1. d = v×t.
2. d = 340 m/s × 7 s.
3. = 2380 m. | waves |
Lines: 28. | null | phy_0276 | worked_example | en | An atom is excited to level n = 8. Count the spectral lines it can emit. | [
"Pairs: 8×7/2.",
"= 56/2.",
"= 28."
] | physics | Answer: Lines: 28.
Steps:
1. Pairs: 8×7/2.
2. = 56/2.
3. = 28. | modern |
Hybnost: 18 kg·m/s. | null | phy_0277 | worked_example | cs | Těleso 6 kg se pohybuje 3 m/s. Spočítej jeho hybnost. | [
"p = m×v.",
"p = 6 kg × 3 m/s.",
"= 18 kg·m/s."
] | physics | Answer: Hybnost: 18 kg·m/s.
Steps:
1. p = m×v.
2. p = 6 kg × 3 m/s.
3. = 18 kg·m/s. | mechanics |
Power: 147 W. | null | phy_0278 | worked_example | en | A current of 7 A flows through 3 Ω. Compute the dissipated power. | [
"P = I²×R.",
"P = (7 A)² × 3 Ω.",
"= 147 W."
] | physics | Answer: Power: 147 W.
Steps:
1. P = I²×R.
2. P = (7 A)² × 3 Ω.
3. = 147 W. | electromagnetism |
Teplota: 289 K. | null | phy_0279 | worked_example | cs | Teplota je 16 °C. Převeď ji na kelviny. | [
"Přičti 273.",
"16 + 273.",
"= 289 K."
] | physics | Answer: Teplota: 289 K.
Steps:
1. Přičti 273.
2. 16 + 273.
3. = 289 K. | thermodynamics |
Apparent depth: 60 cm. | null | phy_0280 | worked_example | en | An object sits 90 cm deep in glass (n = 1.5). Compute the apparent depth. | [
"d' = d/n.",
"d' = 90 cm / 1.5.",
"= 60 cm."
] | physics | Answer: Apparent depth: 60 cm.
Steps:
1. d' = d/n.
2. d' = 90 cm / 1.5.
3. = 60 cm. | optics |
3rd harmonic: 450 Hz. | null | phy_0281 | worked_example | en | A string's fundamental is 150 Hz. Compute its 3rd harmonic. | [
"f3 = 3×f1.",
"f3 = 3 × 150 Hz.",
"= 450 Hz."
] | physics | Answer: 3rd harmonic: 450 Hz.
Steps:
1. f3 = 3×f1.
2. f3 = 3 × 150 Hz.
3. = 450 Hz. | waves |
Rychlé předměty se krátí ve směru pohybu. | null | phy_0282 | concept | cs | Co je kontrakce délek? | [
"Rychlé předměty se krátí ve směru pohybu.",
"Odpověď tedy platí: Rychlé předměty se krátí ve směru pohybu."
] | physics | Answer: Rychlé předměty se krátí ve směru pohybu.
Steps:
1. Rychlé předměty se krátí ve směru pohybu.
2. Odpověď tedy platí: Rychlé předměty se krátí ve směru pohybu. | modern |
Work: 120 J. | null | phy_0283 | worked_example | en | A force of 30 N pushes 4 m. Compute the work done. | [
"W = F×d.",
"W = 30 N × 4 m.",
"= 120 J."
] | physics | Answer: Work: 120 J.
Steps:
1. W = F×d.
2. W = 30 N × 4 m.
3. = 120 J. | mechanics |
Capacitors store charge per volt, smoothing supplies and timing circuits. | null | phy_0284 | concept | en | What is capacitance? | [
"Capacitors store charge per volt, smoothing supplies and timing circuits.",
"So the answer stands: Capacitors store charge per volt, smoothing supplies and timing circuits."
] | physics | Answer: Capacitors store charge per volt, smoothing supplies and timing circuits.
Steps:
1. Capacitors store charge per volt, smoothing supplies and timing circuits.
2. So the answer stands: Capacitors store charge per volt, smoothing supplies and timing circuits. | electromagnetism |
Heat: 50232 J. | null | phy_0285 | worked_example | en | How much heat warms 2 kg of water by 6 K? (c = 4186 J/(kg·K)) | [
"Q = 2 kg × 4186 J/(kg·K) × 6 K.",
"= 50232 J."
] | physics | Answer: Heat: 50232 J.
Steps:
1. Q = 2 kg × 4186 J/(kg·K) × 6 K.
2. = 50232 J. | thermodynamics |
Zdánlivá hloubka je 20 cm. | {
"A": "15 cm",
"B": "25 cm",
"C": "20 cm",
"D": "30 cm"
} | phy_0286 | multiple_choice | cs | Předmět leží 30 cm hluboko ve skle (n = 1,5). Jaká je zdánlivá hloubka? | [
"d' = 30 cm / 1,5.",
"d' = 20 cm.",
"Vyber možnost C."
] | physics | Answer: 20 cm
Steps:
1. d' = 30 cm / 1,5.
2. d' = 20 cm.
3. Vyber možnost C.
Answer: (C) | optics |
Period is 0.25 s. | {
"A": "0.2 s",
"B": "0.17 s",
"C": "0.33 s",
"D": "0.25 s"
} | phy_0287 | multiple_choice | en | A wave has frequency 4 Hz. What is its period? | [
"T = 1 / 4 Hz.",
"T = 0.25 s.",
"Select option D."
] | physics | Answer: 0.25 s
Steps:
1. T = 1 / 4 Hz.
2. T = 0.25 s.
3. Select option D.
Answer: (D) | waves |
300 atoms remain. | {
"A": "250",
"B": "350",
"C": "300",
"D": "400"
} | phy_0288 | multiple_choice | en | A sample of 1200 atoms undergoes 2 half-lives. How many remain? | [
"Halve twice: 1200 → 600 → 300.",
"Left: 300.",
"Select option C."
] | physics | Answer: 300
Steps:
1. Halve twice: 1200 → 600 → 300.
2. Left: 300.
3. Select option C.
Answer: (C) | modern |
Speed is 12 m/s. | {
"A": "11 m/s",
"B": "13 m/s",
"C": "14 m/s",
"D": "12 m/s"
} | phy_0289 | multiple_choice | en | A car travels 120 m in 10 s. What is its speed? | [
"v = 120 m / 10 s.",
"v = 12 m/s.",
"Select option D."
] | physics | Answer: 12 m/s
Steps:
1. v = 120 m / 10 s.
2. v = 12 m/s.
3. Select option D.
Answer: (D) | mechanics |
Resistance times capacitance sets charge speed, timing flashes and filters. | null | phy_0290 | concept | en | Why RC time? | [
"Resistance times capacitance sets charge speed, timing flashes and filters.",
"So the answer stands: Resistance times capacitance sets charge speed, timing flashes and filters."
] | physics | Answer: Resistance times capacitance sets charge speed, timing flashes and filters.
Steps:
1. Resistance times capacitance sets charge speed, timing flashes and filters.
2. So the answer stands: Resistance times capacitance sets charge speed, timing flashes and filters. | electromagnetism |
Power: 100 W. | null | phy_0291 | worked_example | en | An engine does 1000 J of work in 10 s. Compute its power. | [
"P = W/t.",
"P = 1000 J / 10 s.",
"= 100 W."
] | physics | Answer: Power: 100 W.
Steps:
1. P = W/t.
2. P = 1000 J / 10 s.
3. = 100 W. | thermodynamics |
Magnification: 7×. | null | phy_0292 | worked_example | en | An image forms 70 cm from a lens, object at 10 cm. Compute the magnification. | [
"M = di/do.",
"M = 70 cm / 10 cm.",
"= 7×."
] | physics | Answer: Magnification: 7×.
Steps:
1. M = di/do.
2. M = 70 cm / 10 cm.
3. = 7×. | optics |
Speed: 1500 m/s. | null | phy_0293 | worked_example | en | A string wave has f = 500 Hz and λ = 3 m. Compute its speed. | [
"v = f×λ.",
"v = 500 Hz × 3 m.",
"= 1500 m/s."
] | physics | Answer: Speed: 1500 m/s.
Steps:
1. v = f×λ.
2. v = 500 Hz × 3 m.
3. = 1500 m/s. | waves |
Count: 10. | {
"A": "9",
"B": "11",
"C": "12",
"D": "10"
} | phy_0294 | multiple_choice | en | An atom is excited to level n = 5. How many spectral lines can it emit? | [
"Pairs: 5×4/2.",
"Lines: 10.",
"Select option D."
] | physics | Answer: 10
Steps:
1. Pairs: 5×4/2.
2. Lines: 10.
3. Select option D.
Answer: (D) | modern |
Výsledná síla: 10 N. | null | phy_0295 | worked_example | cs | Těleso 5 kg zrychluje 2 m/s². Spočítej výslednou sílu. | [
"F = m×a.",
"F = 5 kg × 2 m/s².",
"= 10 N."
] | physics | Answer: Výsledná síla: 10 N.
Steps:
1. F = m×a.
2. F = 5 kg × 2 m/s².
3. = 10 N. | mechanics |
Moving charges create magnetic fields, turning compasses and motors alike. | null | phy_0296 | concept | en | What is magnetism? | [
"Moving charges create magnetic fields, turning compasses and motors alike.",
"So the answer stands: Moving charges create magnetic fields, turning compasses and motors alike."
] | physics | Answer: Moving charges create magnetic fields, turning compasses and motors alike.
Steps:
1. Moving charges create magnetic fields, turning compasses and motors alike.
2. So the answer stands: Moving charges create magnetic fields, turning compasses and motors alike. | electromagnetism |
Temperature: 294 K. | null | phy_0297 | worked_example | en | Temperature is 21 °C. Convert it to kelvin. | [
"Add 273.",
"21 + 273.",
"= 294 K."
] | physics | Answer: Temperature: 294 K.
Steps:
1. Add 273.
2. 21 + 273.
3. = 294 K. | thermodynamics |
Odpověď je odraz. | {
"A": "lom",
"B": "rozptyl",
"C": "pohlcení",
"D": "odraz"
} | phy_0298 | multiple_choice | cs | Vyber: co se odráží stejně? | [
"Úhly shodné.",
"Tedy: odraz.",
"Vyber možnost D."
] | physics | Answer: odraz
Steps:
1. Úhly shodné.
2. Tedy: odraz.
3. Vyber možnost D.
Answer: (D) | optics |
Shakes run perpendicular to travel, like light and strings. | null | phy_0299 | concept | en | What is a transverse wave? | [
"Shakes run perpendicular to travel, like light and strings.",
"So the answer stands: Shakes run perpendicular to travel, like light and strings."
] | physics | Answer: Shakes run perpendicular to travel, like light and strings.
Steps:
1. Shakes run perpendicular to travel, like light and strings.
2. So the answer stands: Shakes run perpendicular to travel, like light and strings. | waves |
Počet: 3. | {
"A": "2",
"B": "3",
"C": "4",
"D": "5"
} | phy_0300 | multiple_choice | cs | Atom je vybuzen do hladiny n = 3. Kolik spektrálních čar může vyzářit? | [
"Dvojice: 3×2/2.",
"Čar: 3.",
"Vyber možnost B."
] | physics | Answer: 3
Steps:
1. Dvojice: 3×2/2.
2. Čar: 3.
3. Vyber možnost B.
Answer: (B) | modern |
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