RVHS H2 Physics P4 Soln

RVHS JC2 Preliminary Examinations Physics Paper 4 Mark Scheme Question 1 Question Answer Marks 1(a)(i) values of m recorded to correct precision with correct units. 2 d.p. in gram range of m: 20 g to 30 g 1 (ii) absolute uncertainty = addition of absolute uncertainty of m0 and m1. = ± 0.02 g percentage uncertainty correctly calculated and given to 1 or 2 s.f. 1 (b)(i) p in the range of 7.0 cm to 9.0 cm with correct precision and unit 1 (ii) Range of absolute uncertainty Δ𝑝𝑝 ∶ ± 2 mm to ± 5 mm percentage uncertainty correctly calculated and given to 1 or 2 s.f. 1 (iii) (iv) • Difficulty to align bottom edge of cup with the rule • Parallax error when measuring bottom edge of cup • Attach a light hanging string at the edge as a vertical reference line. • Appropriate method to minimize parallax error ( e.g. clamp a grid paper / scaled marking at the side and look perpendicularly at the scale) • Cup swings / equilibrium is disturbed when taking measurements . • S et square touches edge during measurements; this will sway / move the cup.) • Use a retort stand to clamp the set square and ruler. Slowly move them into the edge, avoid contact with the hanging cup. • Difficult to determine edge of cup without marking • Mark the edge of cup with a marker Do not accept: Do not accept: • imprecise measuring cylinder (m is measured accurately using electronic balance) • cup not in equilibrium / cup sways, without explanation (e.g. set square touches the dangling cup during measurement) • switch off the fan / close the window to prevent wind (these are precautions) • Clamp the cup. (Cup must be hanging freely)

(c) Calculations of √p and √m are correct. s.f. of √p and √m follows the s.f. of p and m respectively. 1 (d)(i) Points of student plotted correctly. 1 (ii) BFL evenly distribute points. Anomaly identified and disregarded when drawing BFL 1 (iii) gradient calculated correctly intercept calculated correctly 1 (iv) m = 0 1 p calculated correctly from intercept. p = intercept2 1 (e)(i) New p greater that p in (b)(i) 1 (ii) Correct calculation of percentage difference of 2 constants 1 comparison of percentage difference of constant with percentage uncertainties with correct conclusion 2 (f) • vary m measure θ. or m is the independent variable and θ is the dependent variable. • M to be kept constant 1 Valid method to measure θ : either using protractor with parallax error considered. or using correct trigometry with dimensions described and labelled. Valid method to measure m: E.g. electronic balance table of measurements with appropriate units: θ in degree or radian; m in gram 2 To find m accurately Plot m vs θ Range of θ goes beyond 45o Draw a line at θ = 45o, find value of m by intersection of lines 1 To find maximum θ Pour water into cup until it spills (or jus