RI 9749 2018

RAFFLES INSTITUTION YEAR 5-6 PHYSICS DEPARTMENT 1 9749 H2 Physics 2018 GCE A-Level Suggested Solutions Paper 1 1 A 22 2 2 4 4 2 2 0.05100% 100%100 6.25100% 0.6%22 π π = = ∆∆ ∆= + ∆∆ −× −× ∆   ×= = = LT g Lg T gL T gL T gL gLT T 2 A Let s be displacement and x be distance: 22 1 21 2 For object P: 11 and x 22 For object Q: By symmetry, 0 and 11x area under graph 2( )( ) 2( )( )22 2 2 2 2 4 = = = −= = ×+ ×= pp Q Q s tv tv s t t t tvvv 3 B Impulse change in momentum () 0.080(18 ( 23)) 3.3 Ns = =∆ = − = −− = fi p mv v 4 C Since trolleys stick together after collision, collision is completely inelastic. Momentum is conserved and velocities of both trolleys are the same after collision. Taking right as positive 1 12 12 1 Initial momentum Final momentum () 5.0(4.0) (2.0)( 3.0) (5.0 2.0) 14 7.0 2.0 ms 14 Ns and 2. − = += + + −=+ = = ⇒= =i mu mu m m v v v v pv 10 ms−

RAFFLES INSTITUTION YEAR 5-6 PHYSICS DEPARTMENT 2 5 A Since the broom is balanced at O, the CG of the broom is 1.05 m from end of X. Let m be the mass of the broom, Since the broom is in balance again, 0 0.200(1.05 0.10 0.27) (0.27) 0.504 g m m τ = −− = ⇒= ∑ 6 A arg arg Without the barge: Weight supported by bridge With the barge: Weight supported by bridge Since the barge is floating: Weight supported by brid water water b e waterdisplaced b e waterdisplaced W WWW WW = =+− = ⇒ ge There is no extra weight supported by the bridge waterW= ∴ 7 C 3 3 22 11 3 2 40 184 kW20 P Fv kv Pv Pv P ∝∝ =  = = 8 B Conventional current flows from a higher electric potenti al to lower electric potential. S is at a lower electric potential than R. An electron has a negative charge and has a higher electric potential energy at S (less negative). Point S is lower than point R. Sine GPE = mgh, GPE at S is lower than at R (independent of charge). 9 D Both P and Q are on the same rotating disc => angular velocity is the same for P and Q. Angular displacement is the same for bo th.θ 10 A When the stone is vertically above the centre of the circle: 2 2 Taking downwards as positive: T W Mr T Mr W ω ω += = −

RAFFLES INSTITUTION YEAR 5-6 PHYSICS DEPARTMENT 3 11 C A: Free falling of object. No need rockets B: Gravitational force provides for centripetal force (object moves in circular path) D: initial momentum can provide it with enough energy to travel directly outwards from surface of the earth. C: The rockets need to keep firing for spacecraft to follow a straight line, if not gravitational force will cause it change direction and take on a circular/spiraling path towards earth. 12 D 11 1Since gradient, 1 4 new old PV nRT VP nRT g nT gg = = ∝ = 13 D X: Qnet < 0 i.e. Tx,initial < 30°C Y: Qnet = 0 i.e. Y is at thermal equilibrium with its