TMJC_2025_H2 Physics_P3_Soln

1 Tampines Meridian Junior College 2025 JC2 Preliminary Examination H2 Physics Tampines Meridian Junior College 2025 JC2 H2 Physics Preliminary Examination Paper 3 Suggested Solution 1 (a) Elastic collision: The total kinetic energy (KE of the system) of the colliding bodies is conserved before and after the collision. Or The relative speed of approach of the two bodies is equal to their relative speed of separation. (b) By conservation of linear momentum, ( ) + = + + = + = 2.4 0 4 C1: sub and 4 A A B B A A B B A B p B A m u m u m v m v v v u m m By conservation of kinetic energy ( )   + = + + = + = 2 2 2 2 2 22 1 1 1 1 2 2 2 2 2.4 0 4 C1: sub , 4 A A B B A A B B A B A B A m u m u m v m v v v u m m By relative speeds ( ) − = − − = − 2.4 0 C1: sub A B B A B A p u u v v v v u Note: only two C1 marks available Solving simultaneously with any of the two above equations,   11.44 m s A1Av −=− (c) By conservation of linear momentum, The total momentum of a system of objects remains constant provided no resultant external force acts on the system. Since no external resultant force is acting on the system, ( ) ( ) 1 2.4 0 5 B1: sub and 4 0.48 m s shown A A B B A o B o o p He p o m u m u m v m v v u m m v − + = + + = =  =

2 Tampines Meridian Junior College 2025 JC2 Preliminary Examination H2 Physics (d) [B1] Before collision: uA at 2.4 m s−1 and uB at 0 m s−1 [B1] shape: Smooth and continuous curvature, 0.48 m s−1 label [B1] After collision: vA at −1.44 m s−1 and uB at 0 m s−1 2 (a) 2 2 kinetic energy of the child at Q with resistive force kinetic energy of the child at Q if there is no resistive force 1 2 1 (4.8 )2 [M1]9.81 (7.0) 0.168 Qmv mgh= = = [A1] (b) 2 2 2 2 percentage efficiency 100% 1 2 100%1 2 54(2.1 ) 100% [M1]20(4.8 ) 51.7 % [A1] Q EPE KE kx mv = = = = (c) Any 2: - Energy loss due to work done by resistive force / friction - Sound produced due to collision with the soft board - Deformation of the soft board 3 (a) Gravitational field strength at a point is the gravitational force per unit mass [B1] on a small test mass placed at that point. before collision during collision after collision t v 2.4 0.48 0 Object B Object A −1.44

3 Tampines Meridian Junior College 2025 JC2 Preliminary Examination H2 Physics (b) Gravitational force provides for centripetal force of satellite. [B1] By Newton’s 2nd Law [B1], gravitational field strength must thus be equal to the centripetal acceleration (OR mg = ma → g = a) (c)(i) If obey inverse square law, ( ) ( )2 lg 2lg lgkg g r kr= → =− + [B1] Consider points (7.95, 1.20) and (8.55 , 0) − =−− 1.20 0Gradient = 2 [B1] working (showing coo rdinates) and answer7.95 8.55 Th