JPJC 2026 Collisions Assignment Solutions

2026/JPJC/PHYSICS/9478 1 JURONG PIONEER JUNIOR COLLEGE 9478 H2 PHYSICS COLLISIONS ASSIGNMENT SOLUTIONS 1 (a) Kinetic energy of ball X before collision    2 X X 2 1 2 1 0.24 2.32 0.6348 0.63 J m u    [1] (b) From Fig. 1.2, magnitude of change in momentum of ball    3 area under graph 1 240 5.00 102 F t      [1] 10.60 kg m s [1] (c) Taking rightward as positive,      Y f i Y Y Y Y 0.60 0.12 2.3 p p p m v u v         [1] 1 Y 2.7 m sv  Velocity of ball Y after collision is 2.7 m s −1 to the right. [1]

2026/JPJC/PHYSICS/9478 2 2 (a) By conservation of momentum,                   bullet bullet block bullet+block bullet+bloc k bullet+block0.100 300 4.00 0 4.10 blockm u m u m v v     [1] bullet+block 1 7.317 7.3 m s v    [1] (b) Initial KE of bullet & block    21 0.100 3002 4500 J   [1] Final KE of bullet & block    21 4.10 7.3172 109.8 110 J    [1] Ratio of final KE to initial KE 110 0.02444500  [1] (c) Since there is a change in total KE of system of bullet and block before and after collision, the collision is inelastic. [1]