2023 RI Prelim P1 AS

1 © Raffles Institution [Turn over 2023 Preliminary Examination H1 Physics Paper 1 Solutions 1 D W W FdV Q t t   I I 2 2 3 1kg m sunits of V kg m s AA s m     2 C The average apple is between 70 and 100 grams. Weight = 0.100  9.81 = 0.98 N 3 B When  is zero, F2 = F (largest), F1 = 0 (smallest). When  is 90, F2 = 0 (smallest), F1 = F (largest). 4 C   2 1 1 1 2 2 2 2 1 2 1 2 1 2 1 (4 ) 82 1 (4 ) 82 Hence, 16 8 2 s a a s a a s s a a a a               2 1 2 1 2 At 8 s, 1 82 64 m t s s a a      5 B 2 2 2 2 2 2 2 2 2 2 2 v u as v u as ua s a ua s a                    Hence, the graph of v against s is a “square-root” graph shifted to the right by 2 2u a to the right and then reflected about the vertical line passing through 2 2s u a . 6 C 2 2 2y yv u gy  At the highest point, vy = 0. Hence, 20 2 yu gy  2yu gy Since the maximum height reached is the same for all three paths, uy is the same too. Option A: Sy = uyt + at2, since all three paths end on ground level, time of flight is the same. Path Z has the longest range. Sx = uxt, path Z has the highest horizontal component and the largest initial speed 2 2( ) x yu u u  . Option B: Sy = uyt + at2, since all three paths end on ground level, time of flight is the same. Option D: Path X has the shortest range. Sx = uxt, path X has the lowest horizontal component.

2 © Raffles Institution 7 A By Newton’s second law, taking the direction of F1 as positive, 1 2 1 2 netF ma F F ma F Fa m     Since object was at rest, F2 is initially zero   2 2F v and acceleration is maximum initially. Acceleration then decreases as F2 increases with increasing speed as object accelerates. Acceleration becomes zero eventually when F1  F2 and object travels at constant (maximum) speed henceforth. 8 A W is the force the Earth exerts on the brick and S is the force the floor exerts on the brick. Hence, by Newton’s third law, equal and opposite force to W is the force the brick exerts on the Earth, and equal and opposite force to S is the force the brick exerts on the floor. 9 C Let the mass of trolley be m and the angle the slope makes with the horizontal be . By Newton’s second law, taking the direction down the slope as positive, net sin sin F ma mg ma a g      where g is the acceleration of free fall. Acceleration is independent of mass. 10 D The initial momentum of the 2 kg sphere is 8 kg m s1 to the right. The initial momentum of the 3 kg sphere is 18 kg m s 1 to the left. The total initial momentum (before collision) is 10 kg m s1 to the left. Thus, both spheres cannot come to rest at the same time, otherwise principle of conservation of linear momentum will be violated. 11 A At equilibrium, the lines of action of three forces must meet at a point. The arrows in the vector triangle