EJC 2018 J1H2 Promo P1 Solutions

©EJC 2021 9749/J1H2Promo/2018 EUNOIA JUNIOR COLLEGE JC1 Promotional Examination 2018 General Certificate of Education Advanced Level Higher 2 PHYSICS MARK SCHEME 9749 Sep/Oct 2018 Paper 1 Multiple Choice Q Key Q Key Q Key Q Key 1 B 6 C 11 C 16 D 2 C 7 C 12 A 17 C 3 C 8 C 13 C 18 A 4 D 9 A 14 C 19 D 5 C 10 C 15 C 20 A 1 units must be homogenous units for pressure = 2 12 2 kg m s kg m sm   units for density = 3 3 kg kg mm  to get units of 1 m s , has to be of form pressure density 2 25 9 1800 1 60 let then and 2 2 20 10 0 04 0 4 2 20 0 82 sf sf sf T T T sf T s f T Q Q Q d Q Q v v v v v . d Qd d d .. . .%                               3 car experiences forward force from t = 0 till t = C. car experiences braking force from t = D till t = D. Car max speed at C. 4 energy conserved if no air resistance so initial speed = final speed A is untrue. Ball 1 goes higher so spends more time in air, must have smaller horizontal speed to travel same horizontal distance u below are vertical speeds compare GPE: 1 2 m 2 1 1 2 u m 2 2u mg  4y mg     1 2 2 1 2 2 prove D true 1 2 1 2 or 2 prove 0 20 C wrong at at t y u u s ut tu ut g t t       

2 ©EJC 2021 9749/J1H2Promo/2018 5 car and trailer move with same speed (and acceleration if any) trailer 1trailer system trailer car car car car N 1 m s N 600 400 400 400 400 1200 F F m a F m a a         6 Consider conservation of horizontal momentum:      trolley trolley total final final 1 final 5 1 25 5 35 1 17 m s mm . v . v v . v     . 7 consider extensions separately as the weight manifests as (constant and uniform) tension through both P and Q: P Q total P Q 3 30 3 0 0 m 1 4 x xx x . x     OR springs in series so eff 1 2 12 eff 12 eff total total eff 300 40 3 300 40 1 1 1 0 4 m k k x Fx k k k kk k Fk .k         8 Centre of mass is: for 3 forces in equilibrium, they pass through common point. D9 by PCE, 1 2 m 2vm 2 2 new old 2 05 0 25 gh vh g .v v h .h     10 by PCE 2 2 15 1 2 210 2 5 2 . t s ut at g t mgh g t g P      11 less damping so: graph generally higher than original peak sharper and higher 12 friction provides centripetal force 2W

3 ©EJC 2021 9749/J1H2Promo/2018 13 Consider lift force liftF vertically:          lift 2 lift 22 1 t sin 6 an 60 1 0 cos 68 m s 60 9 81 5000 F F .g mg mv r r v v v         14 A is not always false, geostationary orbit is at a fixed height (so fixed potential  but the mass of satellites themselves are different GPE m B is not always false due to same reasons of different satellite masses D is true, they must rotate once in 24h 15 consider change in GPE          fina