A playground ride consists of a light rigid rod long
PHYSICS · Subjective · A Level · Physics · Further mechanics and thermal physics · Further mechanics and thermal physics
Problem
A playground ride consists of a light rigid rod L=1.20m long, pivoted at its upper end so that it can swing in a vertical plane like a simple pendulum. A small platform of mass 4.0kg is fixed to the lower end. The air exerts negligible damping.
(i) Calculate the natural angular frequency and the natural period of small oscillations of the ride.
(ii) During a fair, an electric motor delivers tiny horizontal nudges of equal strength to the platform every 2.5s. Determine whether these nudges will set the ride into resonance-like large amplitude motion or not. Support your answer with a calculation.
(iii) If the fair organisers wish to achieve resonance, how many such nudges per minute should the motor deliver? Show your working clearly.