Question

A body is moving in a room with a velocity of \[20\,m/s\] perpendicular to the two walls separated by \[5\;m\]. There is no friction and the collision with the walls are elastic. The motion of the body is
A. Non periodic
B. Periodic but not simple harmonic
C. Periodic and simple harmonic
D. Periodic with variable time period

Answer 1

Hint:
Motion is the alteration of a body's position or orientation over time. To solve this problem we should know the concept of elastic collision and the basics of periodic motion.

Complete step by step solution:

In the question, we have given that the velocity of \[20\,m/s\]which is perpendicular to the walls separated by \[5\;m\],
In order to know that when two things come into direct touch with one another, a collision occurs. It is the occurrence where two or more bodies exert forces on one another during a reasonably brief period of time and an elastic collision is one in which the system does not experience a net loss of kinetic energy as a result of the collision. Basically in an elastic collision, the kinetic energy is essentially unchanged and does not change into another type of energy before or after the contact.
A body's motion is referred to as periodic if it consistently performs the same cyclic motion, such as going from point \[A\] to point \[B\] and back again with a fixed time.
As opposed to this, simple harmonic motion is a particular kind of periodic motion in which the acceleration is proportional to the deviation from the mean position. Elastically, the body moves backwards and forwards with a constant time. Body collides into room walls in an elastic way. As a result, there won't be any energy loss and it'll keep bumping into the room's walls, causing periodic motion. The body's energy is unchanged, Therefore there is no acceleration and no simple harmonic motion.
Thus, the correct option is:(B)


Note:
It should be noted that the original energy is preserved, but there is no change in the linear momentum of the entire system. Instead, the involved components' individual momenta change; these changes are equal, opposite in size, and cancel each other out.