Distinguish free oscillations from forced oscillations.
A trolley is supported on a horizontal surface by two stretched springs, as shown in Fig. 4.1. One spring is connected to a fixed point. The other spring is attached to an oscillator that makes the trolley oscillate horizontally. The oscillator vibrates with a constant amplitude of vibration. The frequency of vibration of the oscillator is increased gradually from a very low value. Fig. 4.2 shows the way in which the trolley’s vibration amplitude $x_0$ varies with frequency $f$.
Use Fig. 4.2 to state and explain the trolley’s natural frequency of vibration.
Use Fig. 4.2 to state whether there are any frictional forces acting on the trolley.
The oscillator in (b) is now stopped. The trolley is given a horizontal displacement of $4.7\,\text{cm}$ along the line of the springs. The trolley is then released. Use information from Fig. 4.2 to estimate the maximum speed of the trolley.