Answer to Question #259308 in Classical Mechanics for Light Fury

Question

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

The principle involved here is interference of waves. The wave from the first stone was moving toward him and, most likely, what the boi called wave is the peak above the surface of the water. As he threw the second stone, it created the wave in the opposite direction. The forward motion disturbed the first wave, and, if the wave from the second stone had a crest, it could 'swallow' the peak of the first wave. This is destructive interference.