ADSS Prelim P3 Ans

1 ADMIRALTY SECONDARY SCHOOL 4E PHYSICS MARKING SCHEME PRELIMINARY EXAM 2024 / PAPER 3 SECTION A Qn 1 Answer Marks (aii) (ƟT =) 31.5 ± 0.5 °C 1 (aiii) 100.0 g to 1 dp 1 (bii) (ƟH =) temperature expressed to nearest 0.5 °C. 1 (biv) (ƟF =) temperature expressed to nearest 0.5 °C. 1 (c) cbrass = 0.38 J/(g °C) correct calculation correct unit and precision to least sf (2sf) 1 1 (di) Any two:  some energy is transferred to the internal store of the polystyrene cup (by conduction)  energy is transferred from the internal store of the exposed water surface to the internal store of the surroundings by heating  energy is transferred from the internal store of the cup to the internal store of the surroundings by heating 2 (dii) Any two:  include the mass and specific heat capacity of the glass beaker in the calculation  lag the sides of the beaker to reduce energy transfer via conduction  cover the top of the polystyrene cup with a card to reduce energy transfer via convection 2 Qn 2 Answer Marks (aiii) 31.4 ± 0.2 cm for accuracy (for precision of 0.1 cm and unit) 1 1 (biv) x = 7.0 cm y = 7.6 cm 1 1 (c) 13 g (follow least sf) 1 (d) Constant variables:  Length and mass of the rule (same ruler),  same 10 g mass,  same position where the 10g mass was placed. 1) Set up the apparatus as shown in Fig. 2.4. 2) Place the pivot such that distance between S1 and the pivot, x, is 5.0 cm. 3) Move the position of the 10 g mass until it balances horizontally. 4) Record y, the distance between the pivot and S2, the centre of the 10g mass. 5) Record these values in a table.

2 6) Keeping key variables constant, vary x for four further values of y. Record these values in the same table. 7) Plot a graph of y/cm against x/cm. 8) A straight line of best fit should be obtained, demonstrating that y and x are linearly related. 9) The gradient of the line of best fit is M 10 . The mass of the ruler is 10 × the gradient of the best fit line. x/cm y/cm 5.0 7.0 9.0 11.0 13.0 - for 2 correct constant variables stated - how to vary x as independent variable and measure y as dependent variable - Plot a graph of y against x and correct sketch of best fit line - correct table and heading with units with 5 rows with values of x. - Correctly explain how the mass of the ruler is determined from graph 1 1 1 1 1 y/cm x/cm

3 SECTION B Qn 3 Answer Marks (a) Ensure that the torch, lens and the screen all fall on the same parallel plane. Keep the lens vertically upright, such that the light from the torch will pass through the centre of the lens. Move the screen towards and away the lens along the rule until a sharp image is formed, where any change in X will cause an image that is less sharp. 1 1 1 1 (b) Find average 80.0 cm to 84.0 cm. 1