2017 9749 H2 Physics MS EJC Suggested_ver Jun2022

©EJC 2021 9749/H2 PHYSICS 2017 H2 PHYSICS SUGGESTED SOLUTIONS 9749 November 2017 Paper 1 Multiple Choice Question Key Question Key Question Key 1 A 6 A 11 D 2 B 7 D 12 B 3 C 8 C 13 D 4 D 9 D 14 D 5 C 10 A 15 B 16 C 21 A 26 B 17 D 22 D 27 D 18 C 23 D 28 C 19 B 24 C 29 B 20 C 25 A 30 C Notes: Questions that candidates found more challenging were Questions 5, 12, 14, 15, 16, 17, 21, 22 and 26. Question 5 Option A - a momentum change of less than p would result in the ball continuing to move in the same direction. Option D – an elastic bounce will result in a change of momentum of 2p Question 12 Note that work is done on the system. Question 14 Those who chose option B did not realise that one full cycle corresponds to a rotation of 2π radians. Question 15 Those who chose option A did not realise that frequency is constant as a wave moves from one medium to another. Question 16 Those who chose option A did not recognise that the relationship between ϴ and order n of maxima is not proportional. Question 22 Those who chose option B did not realise that the 2 A current is added to the 4 A current to give 6 A through the bottom 30 Ω resistor. Question 26 Those who chose option C did not recall that the mean power in a resistive load is half the peak power for a sinusoidal alternating current.

©EJC 2021 9749/H2 PHYSICS 2017 Paper 2 Structured Questions Notes: Ensure that all steps in a ‘show that’ question are clearly presented and that all assumptions made are declared. As a logic check, final numerical answers should be realistic. Question Marks 1(a) 3 2 0 (14 10 0 )(9.81 1 ) (10.8 8.0 0 ) F mg x F kx k LL − − ×= =− × = = − M1 1 N49.1 m−= A1 1(b)(i) ( ) 0 00 00 1 () () () 12 100 108 80 12 100 108 80 1249.1 100 108 80 4.0 Nm 2 s.f. mg LL LL L Lkm m km L L k Lm L kk − − ∆ − ∆ +∆∆∆ ∆= += + −− = + −  ∆= +  −  = +  −  =  =  Notes: Portion in square bracket not necessary but as a reminder, if need to evaluate absolute uncertainty, give to more than 1 s.f.. M1 12100% 100%100 108 80 8.1% k k ∆ × = + × − = A1 1(b)(ii) 1 1 8.1 (49.1)100 4 N m (1 s.f.) 49 4 N m k kkk k − − ∆ × = ∆= = ± = ± Notes: When presented in this form, the absolute uncertainty is 1 s.f. and the precision of the quantity follows that of the absolute uncertainty (i.e. in this case, k must be quoted to the nearest ‘1’) B1

©EJC 2021 9749/H2 PHYSICS 2017 Question Marks 1(c)(i) magnitude of upthrust is equivalent to reduction of elastic force for (10.8 - 10.3 =) 0.5 cm of extension C1 2 0.5 cm (49)(0.5 10 2 N ) 0. 5 U kx −= = ≈× C1 A0 1(c)(ii) volume of block, ( ) 3 53 140 10 7750 1.81 10 m block block mV ρ − − ×= = × = Notes: This is not the final answer, so in your calculator/working work with more s.f.’s. M1 Upthrust is the weight of liquid displaced 3 3 140 1