TMJC_2023_H2 Physics_P2_MS

1 Tampines Meridian Junior College 2023 JC2 Preliminary Examination H2 Physics Tampines Meridian Junior College 2023 JC2 H2 Physics Preliminary Examination Paper 2 Suggested Solution 1 (a) 2 2 1 1 2 11.0 (0.80) ( 9.81)(0.80) [M1- correct and v alues]2 2.674 2.67 m s [A0] yy yy y S u t at u Sa u − = + −= +− = = (b) ( ) ( ) 1 tan 10 2.67 [M1]tan 10 15.1 m s [A1] y x x u u u − = ° = ° = (c) (15.1)(0.80) 12.1 m [C1- for calculating best value] 5.0 0.08+ 0.15 [C1: correct substitution]100 0.80 0.15( ) 1.8 m 12 2 m [A1] xx x xx xx xx xx S ut S Su t Sut SS SS = = = ∆∆ ∆= + = = ∆= = ±∆ = ± (d) (i) Air resistance acts in the same direction / downward as the weight of ski jumper. [B1] Hence, the vertical acceleration of the ski jumper is greater than that of free fall or net force is downwards. [B1] Air resistance decreases with decreasing speed. Hence magnitude of vertical acceleration decreases. [B1] At highest point, vertical acceleration is g or free fall (as there is no resistance). [B1] Maximum 3 marks for any of points stated above. (ii) This position increases her surface area to generate upwards lift force. The more the lift, the more time she stays on the flight and thus, the further she will travel. [B1] Or: This position decreases her exposed surface area horizontally (or more streamlined/ reduce the air resistance). Hence, she can travel more horizontally.

2 Tampines Meridian Junior College 2023 JC2 Preliminary Examination H2 Physics Or: This position will lower her CG such that there is a counter moment to the moment created by air resistance. 2 (a) (i) The resultant force in any direction is zero. The resultant torque about any point/axis is zero. [B1] [B1] (ii) [B1] arrow from base of spine and correctly going through the point of intersections of all the forces. (iii) Taking the base of the spine as the pivot, sin12 (0.40) sin70 (0.65) sin70 (0.65) sin12 (0.40) 7.3 QP Q P °= ° °= ° = [M1] [A1] (b) (i) Vertical direction: Fnet = 0 as the suitcase did not move in the vertical direction. 30sin20 11 (9.81) 97.6 N yT NW N N += °+ = = [M1] [A1] (ii) The resultant force acting on the body is proportional to the rate of change of its momentum, and the change takes place in the direction of the resultant force. [B1] (iii) Horizontal direction: Fnet = ma as the suitcase accelerated horizontally. -2 30cos20 8.5 11 1.79 m s xT f ma a a −= °− = = [M1] [A1] base of spine Q P

3 Tampines Meridian Junior College 2023 JC2 Preliminary Examination H2 Physics 3 (a) Rate of change of angular displacement [B1] (b) (i) By conservation of energy, Loss in Ep = Gain in Ek ( )( ) 2 2 1 1 0 [C1]2 19.81 4.5 5.5 [M1]2 14 m s [A0] mgh mv m mv v − = − += = Do n