Catholic High 2023_Year 4 Physics_TA1_with ANSWERS ONLY_Students

CATHOLIC HIGH SCHOOL Term 1 Class Test Year 4 (Integrated Programme) 2023 Answers for Section A 1 D 2 A 3 C 4 D 5 C 6 C 7 C 8 B 9 B 10 C Answers for Section B Remarks 11(a) Pressure is the force acting (perpendicularly) per unit area. [B1] (b) Mark at the lowest point in Fig 11.1 [B1] (c) Let the pressure of the gas be Pg Pressure of gas measured Pressure of gas measured by mercury manometer = by water manometer hmmg + Patm = hwwg + Patm hw = ℎ𝑚𝜌𝑚 𝜌𝑤 hw= 0.05 ×13 600 1000 [B1] = 0.68 m [B1] 12(a) The air molecules are in constant random motion. As the temperature of the gas increases, 1) average KE of air molecules increases / air molecules move faster 2) air molecules hit the walls of the cooker with greater force per unit area 3) frequency of collision of the air molecules on the wall of the cooker increases Hence, pressure in the gas increases (b)(i) Thick wall ensures that the wall can withstand the large pressure, built inside the container (and hence container will not crack) [B1] (ii) The safety valve ensures that some gas can be released to prevent excessive build-up of pressure inside the cooker [B1]

2 13(a) It is the temperature of steam from boiling pure water at one standard atmospheric pressure. [B1] (b) Diagram must show 1) thermometer above water 2) manometer 3) steam out 4) heat source (don’t need Bunsen flame) Set up the thermometer as shown in the diagram above, placing its bulb above the pure boiling water. (The manometer is to check whether the pressure inside the setup is equal to the outside at one standard atmospheric pressure.) [B1] When the liquid level/meniscus is steady in the thermometer , this position is marked as 100 °C. [B1] 14(a) (b) The flame heats up the water at the bottom of the pot, this causes it to expand, becomes less dense and rises. [B1] The cooler denser water above will sink to take its place. The cycle repeats itself and a convection current is set up. [B1] (c) In the wooden chopsticks, the primary mode of heat transfer is molecular vibration.[B1] In the metal chopsticks, besides molecular vibration which is the primary mode of heat transfer, heat can also be transferred by free electron diffusion which is a faster and more efficient mode of heat transfer as compared to molecular vibration [B1]. This will ensure that the user will not experience the high temperature when using the chopsticks.

3 15 (a) (b) Real or not laterally inverted [B1] 16(a) ( ) 3300 1.50 10 vf   = = [B1] 0.200 m = (2 or 3 sf) [B1] (b) The energy from the source spreads out / energy loss to the surrounding air with distance. [B1] (Allow any logical reason.) (c) Twice the frequen