practicals

Question 1

Describe an experiment to determine the value of the Earth’s gravitational field strength g using a simple pendulum and any other appropriate apparatus

Answer 1

-Diagram or description showing a bob suspended from a fixed point, on which the length l may be labelled correctly
-Length l of pendulum measured by ruler from fixed point of support to centre of mass of bob
- Period T measured by stopwatch, by timing a number of oscillations
- Measurement of T repeated for the same l and a mean value of T calculated
-Measurements repeated for at least five different values of l
-Graph of T^2 against l (or any other suitable linear graph) would be plotted
-Graph is a straight line through origin, gradient is 4π2/g
• Small amplitude oscillations.

• Measure l to centre of mass of bob.
• Measure T from a large number of oscillations.
• Repeat timing for each length.
• Begin counting oscillations at nought when t = 0.
• Measure complete oscillations.
• Use of fiducial mark at centre of oscillations.
• Pendulum should swing in a vertical plane.
• Avoid very small values of l when repeating the experiment.