3 11232.03 Question 1 Requirements • 2 × wooden half-metre rules • Thread • Stop-clock • Retort stand, boss head and clamp Preparation Suspend one half-metre rule at a distance of 30 cm below the other, using 2 pieces of thread which are tied in loops around each rule. The loops must be reasonably secure, but free enough to be moved along the rules. Check that there are no splinters! The upper rule should be clamped securely in position above the desk, so that both rules are horizontal and so that the lower rule can complete an oscillation about a vertical axis. Testing Periods of oscillation for the lower rule should fall between approx. 1 s for a 14 cm separation and 0.8 when the strings are separated by 38 cm. Action at changeover The loops of thread should be positioned 18 cm from each end of both upper and lower rules, 14 cm apart, and the arrangement is symmetrical about the centre of oscillation. Re-set the stop-clock.