2022 Sec 4 Physics Prelim Paper 3_Solution

- 2022 Sec 4 Physics PRELIM Paper 3 – Solution Question Answer 1a (i) Measurement to be done using the vernier caliper. 2 d.p in cm for d1. Accept 3 d.p in m. d1 = 0.71 cm Range of 0.69 – 0.73 cm accepted a (ii) Measurement to be done using the vernier caliper. 2 d.p in cm for d2 Accept 3 d.p in m. d2 = 0.72 cm dave = 0.72 cm Range of 0.69 – 0.73 cm accepted Both answers must be correct to get the 1 mark a (iii) Measurement to be done using 50 cm ruler 1 d.p in cm for l and x Accept 3 d.p in m l = 1.0 cm x = 1.5 cm Accept 0.9 cm – 1.1 cm for l Accept 1.3 cm - 1.7 cm for x a (iv) Correct calculation for A. Express value of A to 2 / 3 s.f. A = 2.49 cm2

b(ii) Value of n to whole number. nrice = 3 (range of 2 to 7 accepted.) c Correct calculation for μ. Express value of μ to 2 / 3 s.f. μrice = 0.803 d Value of n should be larger than in b(ii). nsand = 15 Correct calculation for μ. Express value of μ to 2 / 3 s.f. μsand = 4.02 e limitation improvements Not accepted 2 readings insufficient for a conclusion Take more readings and compare values of Repeat/ too few readings Difficult to keep drop height og 3 cm constant Mount a protractor/ marker to makr out height Difficult to release strip without a force Difficult to judge when the mark reaches surface as rice level is uneven Measure change of height of pencil/ place a piece of paper on rice around pencil Rice spills out during the experiment. Conical section of pencil not taken into account affecting l Use a flat ended rod/ thinner pencil 2ai All readings recorded to correct precision of instrument with unit. 1 dp in cm for l0 Accept 3 dp in m Teacher’s value: l0 = 2.1 cm. aii All readings recorded to correct precision of instrument with correct unit. 1 dp in cm for l1, , e0 2 dp in N for F1 Teacher’s value: l1 = 4.1 cm. e1 = 2.0 cm F1 = 0.60 N aiii k correctly calculated with unit and correct s.f. Teacher’s value: k = 0.30 N / cm b(ii) 𝑙2 is measured to the correct d.p

𝑒2, correctly calculated with unit and correct s.f. 𝑙2> 𝑙1 e2> e1 Teacher’s value: l1 = 7.8 cm e1 = 5.7 cm (iii) F2 is correctly calculated with unit and correct s.f (least number of sf between k and e1) F2 = 1.7 N (c) Proposed Solution Independent variable: angle of inclination, θ Dependent variables: 𝑒𝑜 or the force required to applied to the object, F Constant variables: spring of same spring constant, mass of wooden block and metal masses, frictional co -efficient of the surfaces, surface area of the block in contact with the table, Description of experiment: • Set up the experiment as shown in Fig. 2.3. • Raise the spring such that loop of string is now at an angle with the horizontal. • Measure the angle made by the string with the horizontal and adjust the angle to 10º. Record this angle as θ. • Pull the spring until the block ju