RVHS_H2_Physics_P2_Soln

River Valley High School Pg 1 of 7 JC 2 H2 Physics 9749 Preliminary Examinations 2024 RVHS JC2 H2 Physics Prelims Paper 2 Mark Scheme 1 (a) From the measured width of the cubes, take average. Compare the average value to the expected value of 2.0 cm; the closer it is to 2.0 cm, the more accurate is the dimension of the cubes. If the average width is between 1.95 cm and 2.04 cm, it can be considered to be accurate. B1 B1 (b) From the measured width of the cubes, compare the widths of each cube to one another. The closer the widths of each cube, the more precise is the dimensions of his printed cubes. M1 A1 2 (a) The Principle of Conservation of Linear Momentum states that the total momentum of a system remains constant provided no external resultant force acts on the system. B1 B1 (b) An elastic collision between two or more objects is one in which kinetic energy is conserved. B1 (c) initial momentum = (0.400)(5.0) = 2.0 kg m s−1 momentum of P after collision = (0.400)(–0.40) = –0.16 kg m s−1 momentum of Q after collision = 2.0 – (–0.16) = 2.16 kg m s−1 M1 A1 (d) For elastic collision, relative speed of approach = relative speed of separation uP – uQ = vQ – vP 5.0 – 0 = vQ – (– 0.40) vQ = 4.6 m s−1 mQvQ = 2.16 kg m s−1 mQ = (2.16) / (4.6) = 0.47 kg M1 A1 (e) F = Δp / Δt = (2.16 – 0) / (0.060) = 36 N A1 3 (a) (i) The positive direction was defined to be the direction from A to B. ( ) 22 11 24 24 82 31 6.67 10 5.07 10 3.23 10 (0.5 3.85 10 ) 3.31 10 ABGM GMgravitational field strength rr N kg − −− =− + = −  +   =−  Accept 3.31 x10−3 N kg−1 M1 A1

River Valley High School Pg 2 of 7 JC 2 H2 Physics 9749 Preliminary Examinations 2024 (ii) General shape correct. Gravitational potential at surface of A is lower than that at B Marker’s comments: • Many students left a gap between the line to the dotted lines (the surface of both planets). This is not acceptable since the instruction stated specifically to draw from the surface of one planet to the other. Marks cannot be awarded for incomplete diagrams. • Some students drew the curve as if the dotted lines are the asymptotes. This is incorrect, since it suggests that the magnitude of the gravitational potential at the surface of the planet approaches infinity. Incorrect example: B1 (iii) General shape B1 B1

River Valley High School Pg 3 of 7 JC 2 H2 Physics 9749 Preliminary Examinations 2024 Magnitude of g at surface of A larger than that at B and neutral point closer to planet B Marker’s comments: • Similar to previous question, some students drew the curve as if the dotted lines are the asymptotes. This is incorrect, since it suggests that the magnitude of the gravitational field strength at the surface of the planet approaches infinity. (b) (i) • By Newton’s 3rd law of motio