Physics (AS & A Level) · Oct / Nov 2025 · Paper 12 · Question 12

Two different blocks, P and Q, slide towards each other on a horizontal frictionless surface. The blocks have an elastic collision. The diagram shows the velocities of the two blocks immediately after the collision. [diagram: block P moving left at 70 cm s⁻¹, block Q moving right at 20 cm s⁻¹] Which row gives possible velocities of the two blocks immediately before the collision?

1. Avelocity of P: 10 cm s⁻¹ to the right; velocity of Q: 60 cm s⁻¹ to the left
2. Bvelocity of P: 50 cm s⁻¹ to the right; velocity of Q: zero
3. Cvelocity of P: 20 cm s⁻¹ to the left; velocity of Q: 70 cm s⁻¹ to the right
4. Dvelocity of P: 60 cm s⁻¹ to the right; velocity of Q: 30 cm s⁻¹ to the left

As printed in the paper