DHS 2023 JC1 Physics Revision (Set A Solutions)

1 1 DHS @2023 Dunman High School Year 5 Holiday Home Revision Set A Answers 1 (a) m Tv l= 0095.0 )50.1(20= [M1] = 56 m s-1 [A1] (b)      ++= m m T T v v l l 2 1 = ( )02.001.005.02 1 ++ = 0.04 [C1] Δv = 0.04 x 56 = 2.2 [M1] v = (56 ± 2) m s-1 [A1] 2 (a) s = ut 150 = (45 cos 50)t [M1] t = 5.19 s [A0] (b) s = 2 2 1 atut + = (45 sin 50 × 5.19)+ 2)19.5)(81.9(2 1 − [M1] = 47 m [A1] (c) v2 = u2 + 2as 0 = u2 + 2 (−9.81)(47) [M1] u = 30 m s-1 [A1] (d) v = u + gt 0 = 30 + (−9.81)t [M1] t = 3.1 s [A1] Time to throw the apple after launch of arrow is 5.19 – 3.1 = 2.1 s. [A1] 3 (a) The principle of conservation of momentum states that the total momentum of a system of bodies is constant [B1], provided no external resultant force acts on it [B1]. (b) Elastic potential energy stored by spring = 21 2 kx = 21(1330)(0.15)2 = 14.96 J [M1] Elastic potential energy stored by spring = Change in kinetic energy of A 2114.96 (1.5) 02 v=− v = 4.47 m s−1 [A1] (c) Let the common final velocity be v2. By conservation of momentum,

2 2 DHS @2023 m(4.47) = (2.5m) v2 (m = 1.5 kg) [M1] v2 = 1.79 m s−1 [A1] (d) By conservation of energy, ki pi f kf pfE E W E E+ + = + 2o1(2.5 )(1.79) 0 ( 8.5)( ) 0 (2.5 )(9.81)( )(sin3 0)2 m s m s + + − = + [M1] s = 0.223 m [A1] 4 (a) Resultant force on it must be zero in any direction. [B1] Resultant torque on it must be zero about any axis of rotation. [B1] (b) (i) (ii) Let x be the distance of c.g of beam from the hinge. By principle of moments, Taking moments about hinge, Sum of clockwise moments = sum of anticlockwise moments 0 0 0 0 0 0120sin40 (5sin70 ) 120cos40 (5cos70 ) (5 9.81 )( 5sin70 ) (20 9.81 )( sin70 )x+ =  +  [M1] x = 1.57 m [A1] (iii) Vertical summation of forces: 0(120)sin40 5 20YF g g+ = + FY = 168.1 N Horizontal summation of forces: [C1] 0(120)cos40XF = FX = 91.93 N 2222 )1.168()93.91( +=+= Yx FFF [M1] weight of beam force by wall on beam 40o weight of load tension, T β All forces correctly labelled. [B1] Correct directions of forces. [B1]

3 3 DHS @2023 = 192 N 168.1 91.93tan = β = 610 [A1] 4 (c) 5 (a) R cos θ = mg [C1] R cos 20.00 = 1450 (9.81) [M1] R = 1.51 × 104 N [A0] (b) 90 km