2021 J2 H2 Physics Prelim P3 MS Sharing

Anglo-Chinese Junior College 2021 H2 Preliminary Exam Paper 3 MS H2 (9749) Physics JC2 2021 Page 1 of 12 Annotations used in marking BOD - Benefit of doubt ECF - Error carried forward POT - Powers of ten error TE - Transfer error CE - Calculation error XP - Wrong physics ENG - Generally bad english, phrasing and expression PP - Poor presentation of answers Note: For POT and TE, we can award the M mark, not the A mark. Qn Suggested MS 1 (a) Weight of cylinder = Ahρg Pressure = F Ah g AA  (b)(i) An ideal gas is one where there are no intermolecular forces. An ideal gas obeys the ideal gas law pV = nRT where p = pressure, V = volume, n = number of moles, (R = molar gas constant) and T = thermodynamics temperature (b)(ii) Since it is in equilibrium, the pressure of the trapped gas is the sum of the atmospheric pressure and the pressure due to the weight of the mercury. ( ) 0.190om nRTpp A   (b)(iii) Recognize that nRT A is a constant OR 190 po + 190 pm = 208 po - 208 pm pm = 0.035 × 1.36 × 104 × 9.81 = 4.67 × 103 Pa po = 1.03 × 105 Pa (b)(iv) Since temperature stay constant, there is no change to the internal energy of the gas. Negative work done results in a postive Q since ΔU=0.

Anglo-Chinese Junior College 2021 H2 Preliminary Exam Paper 3 MS H2 (9749) Physics JC2 2021 Page 2 of 12 2 (a) The total final momentum of a system after a collision is equal to the total initial momentum of a system before the collision provided that the net external force acting on the system is zero. (b)(i)      1.2 6.40 5.2 0.30 1.2 5.2 A A B B A A B B AB m u m u m v m v vv       6.10 or 6.10 A B B A AB BA u u v v vv vv          1 1 1.2 5.2 6.10 9.24 or 1.2 6.10 5.2 9.24 3.5125 m s 2.5875 m s AA BB A B vv vv v v             -12.59 m s shown (b)(ii) Considering B       5.2 2.59 0.3 11.895 p  11.895 25.31 N0.47 pF t Using Newton’s 3rd law, force A exerts on B is equal in magnitude but opposite in direction to the force B exerts on A, therefore the force B on A will be -25.31N b)(iii) Correct label for uA, vA and straight line before t and after t + 0.47 Straight line with negative slope between t and t + 0.47

Anglo-Chinese Junior College 2021 H2 Preliminary Exam Paper 3 MS H2 (9749) Physics JC2 2021