Energy, damping and resonanceEdexcel A-Level Physics: Flashcards

Exam questions on Energy, damping and resonance

1. A trolley of mass 0.50 kg is held between two identical springs on a horizontal, frictionless track. It is pulled aside and released, and then oscillates with simple harmonic motion with amplitude 0.060 m and period 1.2 s. Air resistance is negligible.
   Calculate the maximum kinetic energy of the trolley.2 marks
2. The drum of a washing machine is mounted on springs and has a natural frequency of vibration of 8.0 Hz. During the spin cycle the motor speed increases steadily from 0 to 20 Hz, so the drum is driven by a periodic force at the spin frequency.
   Explain why the vibrations of the drum become very large as the spin frequency approaches 8.0 Hz.2 marks
3. The body of a car on its suspension behaves as a mass on springs with a natural frequency of 1.5 Hz. The car is fitted with oil-filled shock absorbers. It is driven along a road with evenly spaced ridges, and at one particular speed the ridges push the car upwards 1.5 times every second.
   The car hits a single bump and its body oscillates vertically. Explain what happens to the amplitude and to the total mechanical energy of the oscillation as the shock absorbers act.3 marks