EJC 2023 J1 H2 Promo P2 MS

©EJC 2023 9749/J1H2PROMO/2023 EUNOIA JUNIOR COLLEGE JC1 Promotional Examination 2023 9749 PHYSICS MARK SCHEME Paper 2 Structured Questions s/n Answer Marks 1(a) Velocity is the rate of change of displacement Examiner comments Well done by those who memorized the definition. Students are reminded to use definitions from EJC notes as extra words or lack of key words used may unintentionally convey a different meaning. B1 1(b) v2 = u2 + 2as = 2(4)(30) = 240 v = 15.49 = 15.5 m s -1 (3 s.f.) Examiner comments The given acceleration of 4 m s─1 along the slope is due to the resultant force of the weight of the car, the normal force on the car by the slope, and the friction on the car by the slope. Being a “show” question, it was crucial that the substitution to the correct formula is shown clearly. M1 Correct substitution A0

2 ©EJC 2023 9749/J1H2PROMO/2023 s/n Answer Marks 1(c) Method 1 ux = vx = 15.5 cos 27° = 13.81 m s-1 Taking downward as positive: vy2= uy2+ 2aysy = (15.5 sin 27°)2 + 2(9.81)(40) vy = 28.9 m s-1 2 2 -1 -113 8 28 8 32 m s or 32 0 m s =+=v. . . 1 28 9 64 or 64.5 to the horizontal 13 81θ == °°- .tan . Method 2 Gain in KE = Loss in GPE 22 22 1 1 ()2 1 ( 15 5 ) (9 81)(40)2 32 m s m v u mgh mv . m . v − −= −= = 1 15 5 cos 27cos 64 to the horizontal 32 o.θ −= = ° Examiner comments After point B, the only force acting on the car is its vertically downward weight. The direction of the velocity of the car at point B has both horizontal and vertical components. C1 C1 A1 A1 1(d) Consider vertical direction taking downwards as positive: s = ut + ½ at 2 40 = (15.5 sin 27°)t + ½ (9.81)t 2 t = 2.22 s or -3.66 (rejected) Examiner comments Since the horizontal component of the velocity of the car does not change and horizontal displacement is not given, candidates should use only the vertical component of the velocity to calculate time. M1 A1 32 15.5 cos 27o θ

3 ©EJC 2023 9749/J1H2PROMO/2023 s/n Answer Marks 1(e) Examiner comments Candidates should write 1.82 instead of 4sin27° on the ay axis. The positions of 9.81 and 1.82 on the ay axis should be roughly proportional to their magnitude. B1 1.82 m s-2 from B to C B1 9.81 m s-2 from B to C 1.82 9.81

4 ©EJC 2023 9749/J1H2PROMO/2023 s/n Answer Marks 2(a) Hooke’s Law states that the change in length of a material is directly proportional to the force applied on it, provided that the limit of proportionality is not exceeded. Marker’s Comments Most students were penalised for mis