Chapter 11, Problem 22Q

To determine

Why the waves move from the centre to the rim, or from the rim to the centre, depending on whether you strike at the centre or at the rim, in a round bowl of water.

Explanation of Solution

The waves are a very particular phenomenon, which transmit energy, but without transporting matter. For example, hitting the surface of the water once with your finger causes an alteration in the surface of the water that spreads away from the point where the disturbance occurred (what is known as a source). What spreads is not water, but the disturbance, which is energy.

The basic unit of a wave is the pulse. A pulse is a portion of energy that propagates in space as a disturbance, which in some cases can be a deformation. A succession of pulses forms a wave.

The pulses can be produced by periodically hitting the surface of the water.

When hit on the edge of the bowl, a change occurs in the source or origin of the disturbance and the wave propagates away from it. In the same way, energy is transported, without transporting matter.

After motion, the molecules of water will always find the new equilibrium or level.

Conclusion:

The form of dispersion of the wave depends on the source of propagation of the same.