A student performs three separate experiments with a simple pendulum of the same length
PHYSICS · Subjective · A Level · Physics · Further mechanics and thermal physics · Further mechanics and thermal physics
Problem
A student performs three separate experiments with a simple pendulum of the same length ℓ.
Experiment A: The pendulum is displaced slightly and released in air. No further action is taken.
Experiment B: The pendulum bob is coated with oil to increase air resistance and then released as in Experiment A.
Experiment C: The pendulum from Experiment B is now subjected to small periodic pushes every time it passes through the mean position; the interval between successive pushes equals the time period observed in Experiment A.
Answer the following questions:
(i) For each experiment, state the type of oscillation that occurs and describe qualitatively how the amplitude varies with time.
(ii) On the same set of axes draw three separate curves of amplitude versus time (no numerical values required) corresponding to Experiments A, B, and C, labelling each curve clearly.
(iii) Explain, in not more than four sentences, the physical reasons for the differences among the three curves you have drawn.