YIJC 2023 H2Phy Prelim P1 Solution

2023 YIJC Preliminary Examination H2 Physics Paper 1 Answer Key Question Answer Question Answer Question Answer 1 C 11 B 21 B 2 D 12 B 22 C 3 B 13 B 23 D 4 A 14 B 24 A 5 B 15 B 25 A 6 C 16 D 26 B 7 C 17 C 27 D 8 A 18 B 28 D 9 B 19 C 29 D 10 B 20 A 30 C S/N Ans Explanation 1 C V = 4/3 r3 = 4/3  (d/2)3 V/V  100% = 3d/d  100% = 3(0.01/6.00)  100% = 0.5% 2 D The goods train will overtake the express train after time t when their displacement from the station is the same. For the good train: s1 = ut = 10t For the express train: s2 = ut + ½ at2 = 0 + ½ (0.50)t2 When s1 = s2, 10t = ½ (0.50)t2 t = 40 s 3 B Backward push by back wheel on the road Action and reaction pair will be forward push by road on the back wheel 4 A Looking at FBD of whole system F = ma (5)(9.81) – (2)(9.81) sin 30 – 7.0 = 7a a = 4.61 m s-2 Looking at FBD of 5.0 kg block, F = ma (5)(9.81) – T = 5(4.61) T = 26 N

2 9749 / YIJC / 2023 / JC2 Preliminary Examination / Paper 1 5 B The bar is in equilibrium and the load (weight = W) is a constant. The position of the pivot is also fixed. Let it be a distance h away from the fixed load. Taking moments about the pivot, Wh = Fx Wh is a constant since W and h are constants. Hence, Fx = constant F  1/x Graph B shows this relationship. 6 C A body in equilibrium and acted on by three forces (R, W and tension in the thread), the line of action of these three forces must pass through a common point. Only option C is correct. 7 C (A) While the direction of the velocity of the ball can change after bouncing, the kinetic energy remains positive (no direction for kinetic energy). (B) The power generated by the engine can be equated to the gravitational potential energy gained per unit time and rate of work done against friction. (C) Since the appliance is an electric heater, all the energy output can be lost in terms of thermal energy. Thus, it is possible to have the electric heater at 100% efficient. (D) Momentum must be conserved in a collision. 8 A For object moving in uniform circular motion, the net force (centripetal force) points towards the centre of the circle. Since there is no displacement in the direction of the net force, work done by F is zero. 9 B The glue will snap at the lowest position of the vertical circular motion. T – W = mr2 18 – 3 = (3/9.81)(0.85) 2  = 7.6 rad s−1 10 B Moving at right angle to the vertical gravitational field implies that the object is still at the same level as before. Since the field is uniform, there is no change in the gravitational potential energy of the object. 11 B At constant power, a longer line means a longer time duration and therefore more heat transfer. Q is melting and S is boiling. Since S is longer, the specific latent heat of vaporisation is larger than the specific latent heat of fusion. 12 B For tot