# Mock exam paper C Ordinary Level Marking Scheme

Pre-Leaving certificate Examination 2013

Physics- Higher level

W: http://www.irevise.com/ T: 091 - 520400 1. In an experiment to verify the principle of conservation of momentum the following results were obtained

Mass of trolley A=100g

Mass of trolley B =150g

Distance travelled by A in 0.2s before collision=5cm

Distance travelled by A and B in 0.2s after collision =2cm

Draw a diagram of the apparatus used in this experiment (9)

Diagram to include Trolleys, airtrack, means of joining trolleys, method to measure velocity (3x3)

Calculate (i) the initial speed of the trolley A (6)

Speed = dist / time = 0.05/0.2 = 0.25 ms-1

(ii) The speed after the collision of the two trolleys (6)

Speed = dist / time = 0.02/0.2 = 0.1 ms-1

Use the data from the experiment to verify the principle of conservation of momentum. (12)

Momentum before = momentum after (3)

M1u1 + m2u2 = (m1+m2) v (3)

0.1(0.25) + (0.15)(0) = 0.25 (0.1) (3)

0.025 = 0.025 (3)

List two possible sources of error in the experiment and what steps you would take to minimise these errors (7)

Any two relevant errors (4 + 3)

1. The student performed an experiment to measure the focal length of a concave mirror. The following table of results were obtained
 Object distance from mirror (u) /cm Image distance from mirror (v) /cm 29 64 37 43 40 41 50 35 55 33 60 30

Describe how the image position was located (9)

Explain steps, no parallax, object outside f (3x3)

Plot a suitable graph and, from the graph, calculate an average value for the focal length of the mirror (24)

Calculate and tabulate 1/u and 1/v (3)

Axes correctly labelled (3)

At least 5 points plotted correctly (3)

Straight line drawn (3)

Intercepts measured (6)

Intercepts averaged for 1/f (3)

Calculate f (3)

Give two sources of error in measuring the image distance and state how one of...