Transverse & Longitudinal Waves (CIE AS Physics)

Explain what is meant by a progressive wave.    

An elastic cord is fixed at one end and attached to a mechanical oscillator at the other end. Fig. 1.1 shows, at time t = 0, the shape of a section of the cord as the wave travels from left to right. W, X, Y and Z are four marked points on the cord.

The mechanical oscillator has a steady frequency of 5.0 Hz. The wave has a wavelength of 0.60 m and an amplitude of 0.030 m.

On the axes of Fig. 1.2 sketch the graph of the displacement of point X over the period t = 0 to 0.40 s. Add suitable scales to the axes.

For time t = 0, state which of the points W, X, Y and Z   

The speed of point W on the cord at t = 0 is 0.94 m s^–1. With the cord at its original tension, the frequency of oscillation is now doubled to 10 Hz.

The amplitude is kept at 0.030 m. Calculate the new speed of point W at t = 0. Explain your reasoning.

Explain briefly how transmission of energy by a longitudinal wave differs from transmission of energy by a transverse wave. Give one example of a transverse wave.

With the aid of a clearly labelled diagram explain how a sound wave in air transmits energy away from its source.

Short pulses of sound are reflected from a wall 30 m from the sound source. The reflected pulses return to the source after 0.18 s.

Calculate the speed of sound.

Fig.1.1 represents the sound wave from part (c).

Fig. 1.1

Calculate the frequency of the sound wave.

A large water tank is set up so that a wave can be generated at each end of the tank. The two waves, A and B, travel towards each other at the same speed.

Fig. 1.1 shows the variation of displacement of the water surface with distance travelled at a particular instant.

Fig. 1.1

Deduce how many times greater the amplitude of B is to the amplitude of A.

Wave A has a frequency of 8.0 Hz.

Fig. 1.1 

Explain how the stationary wave is generated in the tank.