Prelim H2P1 MS

1 Anderson Serangoon Junior College 2021 H2 Physics Prelim Mark Scheme Paper 1 (29 marks) 1 2 3 4 5 6 7 8 9 10 C D C D A B D B D B 11 12 13 14 15 16 17 18 19 20 A B A A A D C C B C 21 22 23 24 25 26 27 28 29 30 B C D D B A C B B 1 C coin mass – 10–3 kg; paper thickness – 10–4 m; body temperature – 102 K 2 D d2 – d1 = 3.46 mm (d2 – d1) = (d2) + (d1) = 0.03 + 0.02 = 0.05 mm 3 C Initial velocities for both stones, u = 0 s = ut + ½ gt2 = ½ gt2 For the same time interval, Δt, both stones fall down by the same distance, s. Therefore the distance between them will always remain the same as that at the point of release. 4 D Since bathroom scales reading (which is equal to contact force from scale on person) is less than weight, the net force on person is downwards. The acceleration of the person is directed downwards. This applies either when the person is moving downwards is speeding up, or when the person is moving upwards and slowing down. A and C are wrong as the person has acceleration, so cannot be moving at constant speed. B is wrong. When movement is downwards and slowing down, acceleration is upwards. 9749/01/ASRJC/2021PRELIM [Turn Over contact force from scale person weight

2 5 A System of two mass: F = 3 (a) a = System of 1 kg mass: T = (1.0) () = 6 B For elastic collisions, the relative speed of approach equals relative speed of separation u 0 = ‒ v2 ‒ v1 v2 = u + v1 (1) From conservation of linear momentum mu + 0 = mv1 + 4mv2 (2) Substituting (1) into (2) mu = mv1 + 4m(u + v1) 5v1 = 3‒ u v1 = 7 D To have only rotational motion, net force = 0 but net moment  0. B and C are wrong as net force is not zero, so system causes linear movement of the rod. A is wrong as moments about any point is zero, hence no rotational movement. D is correct as moments about any point is not zero, hence there is rotational movement. 8 B P = Fv = F(u + at) = F(0 + at) = Fat Since F and a are constants, P varies linearly with t. 9 D Both boats travel the same distance s and experience the same force F. Hence the total work done by the force F between the starting line and the finishing line is the same for each boat – they will have the same final kinetic energy. Boat with mass m will experience a larger acceleration, and will thus reach the finish line first. Note: Boat with mass m will also have a higher speed, since the two boats have the same final kinetic energy. 10 B 9749/01/ASRJC/2021PRELIM

3 Compare mechanical enery at hilltop to that at top of loop. By Conservation of Energy, 11 A Since  = , magnitude of g = = Potential at P > potential at Q since mass loses potential energy as it moves from P to Q. Hence, direction of g is from P to Q, higher potential to lower potential. 12 B R