JPJC 2026 Collisions Assignment

2026/JPJC/PHYSICS/9478 1 JURONG PIONEER JUNIOR COLLEGE 9478 H2 PHYSICS COLLISIONS ASSIGNMENT 1 Two balls X and Y of equal diameter but different masses 0.24 kg and 0.12 kg respectively, slide towards each other on a frictionless horizontal surface, as shown in Fig. 1.1. Fig. 1.1 Both balls have initial speed 2.3 m s −1 before they collide with each other. Fig. 1.2 shows the variation with time t of the force Fy exerted on ball Y by ball X during the collision. Fig. 1.2 Calculate (a) the kinetic energy of ball X before the collision, [1] (b) the magnitude of the change in momentum of ball Y, [2] (c) the velocity of ball Y after the collision. [2] 11

2026/JPJC/PHYSICS/9478 2 2 A 100 g bullet fired from a gun penetrates a 4.00 kg stationary block with a speed of 300 m s −1. The block then moves backwards along a frictionless ground, with the bullet remaining inside the block, as shown below. (a) Calculate the speed of the block after being hit by the bullet. [2] (b) Calculate the ratio of the kinetic energy of the system after the collision to that before the collision. [3] (c) Deduce, with a reason, whether the collision is elastic or inelastic. [1] block moves after being hit initial position of block