# GCSE Physics Revision: General Physics Alternative to Practical

A student carries out an experiment using a simple pendulum. The figure below shows the apparatus.

The student records the time t taken for 20 complete oscillations for a range of different lengths x of the string. The readings are shown in the table.

The length l of the pendulum is given by the equation l = x + r, where r is the radius of the pendulum bob.
The figure below shows the pendulum bob drawn actual size.

(a) (i) Use your rule to measure the diameter d of the pendulum bob.
(ii) Calculate the radius r of the pendulum bob.

(b) (i) Complete the column for the length l / cm in the table using the equation l = x + r.
(ii) The period T is the time taken for one complete oscillation. Complete the column for the period T / s in the table.

(c) Plot the graph of T / s (y-axis) against l / cm (x-axis). Start the T / s axis at T = 1.0 s.

(d) Using the graph, find the length la of the pendulum that would have a period of 1.50 s.