| Syllabus | Alternate Universe Cambridge 0625 |
| Subject | Physics (0625) Extended |
| Paper | 0625/42/M/J/25 · Paper 4, Variant 2 |
| Also listed as | 0625_s25_qp_42 · 0625_s25_ms_42 |
| Session | May/June 2025 |
| Questions | 10, multiple choice, with answers and explanations |
| Cost | Free |
0625/42/M/J/25 answer key
Preview the first questions
Question 1
An ice skater moves at a constant speed of 11 m/s for 3.0 s. What distance does she travel during this time?
- 33 m
- 3.7 m
- 14 m
- 0.27 m
Show the answer and explanation
Correct answer: A
For motion at constant speed, distance = speed times time = 11 x 3.0 = 33 m. This is also the area under a horizontal speed-time graph of height 11 m/s over 3.0 s.
Question 2
A uniform wooden metre ruler has length 1.0 m, width 2.6 x 10^-2 m and thickness 6.0 x 10^-3 m. Its mass is 0.081 kg. What is the density of the wood?
- about 520 kg/m^3
- about 5200 kg/m^3
- about 52 kg/m^3
- about 1.6 x 10^-4 kg/m^3
Show the answer and explanation
Correct answer: A
Volume of the ruler = length x width x thickness = 1.0 x 2.6 x 10^-2 x 6.0 x 10^-3 = 1.56 x 10^-4 cubic metres. Density = mass divided by volume = 0.081 / (1.56 x 10^-4) = about 520 kg/m^3.
Question 3
Train A (0.45 kg) moves at 0.34 m/s to the right and train B (0.21 kg) moves at 0.12 m/s to the left. They collide and stick together. What is the velocity of the combined trains immediately after the collision?
- about 0.19 m/s to the right
- about 0.27 m/s to the right
- about 0.23 m/s to the left
- 0 m/s (they stop)
Show the answer and explanation
Correct answer: A
Momentum is conserved. Take rightward as positive. Total momentum before = 0.45 x 0.34 + 0.21 x (-0.12) = 0.153 - 0.0252 = 0.1278 kg m/s. Total mass after = 0.45 + 0.21 = 0.66 kg. Velocity after = 0.1278 / 0.66 = about 0.19 m/s, positive, so to the right.
Worked answers: questions 4 to 10
Why each answer is right. The full questions are waiting in every Paperverse world, with your mark at the end.
Question 4 · Answer A
At a given temperature, a dull black surface is a much better emitter of infrared radiation than a shiny white surface. Container A therefore radiates thermal energy away faster than container B, and so its water cools more quickly.
Question 5 · Answer A
Use the wave equation: speed = frequency times wavelength, so wavelength = speed / frequency. Convert 2.48 GHz to 2.48 x 10^9 Hz. Then wavelength = (3.0 x 10^8) / (2.48 x 10^9) = about 0.12 m.
Question 6 · Answer A
Placing the object at twice the focal length (2F) of a converging lens produces an image at 2F on the opposite side. The image is real, inverted, and the same size as the object. This is a standard case of the converging lens.
Question 7 · Answer A
One kilowatt-hour is the energy used by a 1 kW device in 1 hour. The lamp's power is 25 W = 0.025 kW. Energy = power x time = 0.025 kW x 220 h = 5.5 kW h.
Question 8 · Answer A
Resistance = potential difference divided by current. So R = V / I = 5.0 / 2.4 = about 2.1 ohms.
Question 9 · Answer A
An alpha particle has proton number 2 and nucleon number 4. In alpha decay the parent nucleus loses two protons and two neutrons, so the proton number drops by 2 (from 88 to 86) and the nucleon number drops by 4 (from 223 to 219). The product is therefore radon with proton number 86 and nucleon number 219.
Question 10 · Answer A
After its stable phase, a massive star swells into a red supergiant. When it can no longer support itself by fusion it explodes as a supernova. The core left behind collapses to form a neutron star or, if massive enough, a black hole.