Answer to Question #259289 in Mechanics | Relativity for Vivoz

Question

3. One day a teen boy went out of their house and stood beside a pond. He threw a small rock in

the pond relatively far from him and found that a nice wave was coming toward him. He felt a

lovely moment. He threw another similar stone in the pond relatively close to him. He found

that the first wave was disturbed and was not coming to him smoothly. He tried to understand,

‘why did it happen?’ but failed and become unhappy. How will you explain this incidence in

details to the boy to make him so happy? Please mention the principle involved in the incident

and explain different cases of its applications.

Answer 1

If two identical waves (progressive) travel with the same speed in the opposite directions then due to the superposition of these two identical progressive waves a stationary wave is formed in medium.

For progressive waves, the disturbance travels forward but in the case of stationary waves, the disturbance does not travel at all. When the boy threw a small rock in a pond relatively far from him the progressive wave was created in water and propagated outside the point where the rock threw. When he threw another stone in the pond relatively close to him another progressive wave was created at the same speed. When the second identical wave is superimposed with the first one then created a stationary or standing wave in water that does not travel at all. So, the first wave does not come to him, but the water molecule vibrates up and down. It is due to the action of a boy.