EJC 2022 Prelim P3 Guide

©EJC 2022 9749/J2H2MYE/2022 ; EUNOIA JUNIOR COLLEGE JC2 MID-YEAR EXAMINATIONS 2022 9749 PHYSICS MARK SCHEME Paper 3 Longer Structured Questions Qns Answer Marks 1(a)(i) gravitational force of attraction per unit mass acting on (OR experienced by) a small test mass placed at that point (in the gravitational field) 1 1(a)(ii) gravitational force of attraction between two point masses is directly proportional to the product of the masses and inversely proportional to the square of separation between the masses Let m be the mass of an object distance R away from Mass M field strength is gravitational force of attraction per unit mass experienced by small test mass placed at that point 1F m m = GM m 22 GM rr = 1 1 1 1(b)(i) ( ) ( )     − =  = = =  = =  3 30 16 3 3 4 13 4 3 3 8.245 10 4volume of star 3 4 2.7 10 2 10 7.54 212 0m 3 6. m 3 .7 10 kg r m v 1 1 1(b)(ii) (words to effect of) density increase closer to centre (words to effect of) outer layers compress inner layers 1 1

2 ©EJC 2022 9749/J2H2MYE/2022 Qns Answer Marks 1(b)(iiI) By conservation of energy: ( )( ) 2 11 30 4 81 2 6.67 6.22 oss in KE gain inl 1 10 10 10 2 2. 1.75 1 GP 0 m 7 E 00 s GM G mm mv r v r − − = = − = = − −   =    1 1

3 ©EJC 2022 9749/J2H2MYE/2022 Qns Answer Marks 2(a) oscillatory motion where acceleration is directly proportional to displacement from equilibrium position and directed opposite to displacement 1 2(b)(i) 0 2 2 2 00 1 2 2 2 a 2 2 0.74 mplitude 0.7 . m m 00 1 . .0 2 5 s x xT xxvx   − = − = − =     = − = 1 1 2(b)(ii) ( ) 00 00 0.15 0.55 22 0.7 2.1374 relative to equilibrium relative to groun d m m OR sin sin 0.7 sin 0.55 sin 20.15 0.7 sin d uration 4.0 xx x x x x xx T t tt T tt   =− = ==     +  −=   +    =    = =      ( ) ( )C 8 7 s 0. a 137 48 2 c n be by G .2 −− = 1 1

4 ©EJC 2022 9749/J2H2MYE/2022 Qns Answer Marks 3(a)(i) ( ) ( ) ( ) ( ) v loss loss v l 2 1 2 v 1 os 2 s 1v 1 1 loss 2v 2 2 1 1 1 2 2 v 12 ____ 1 2 ____ 2 1 m E mL h Pt hmP tt mm tt V m m m tt P hmPL h L P P L P t V t tt L t L P = + = =    =−       =     −        =+     =+    + − − − =  −II ( )( ) ( )( ) 12 61 33 5.0 78 4.0 60 16 10 10 10 1. 2.25 10 1 J k 5 g 60 .5 60 m t −− −   − −=  − =        1 1 A0 3(a)(ii) pure substances undergo phase change at constant temperature (words to that effect) so temperature difference wi