Final answer:
The amplitude of simple harmonic motion remains the same after an elastic collision, but the motion will be symmetric around a new mean position, leading to a new amplitude on each side of the mean.
Step-by-step explanation:
When a block of mass m attached to a spring undergoes simple harmonic motion (SHM) and collides elastically with a wall placed at a distance x (x < A), where A is the amplitude, the amplitude of the motion does not change. However, the motion will be symmetric around a new mean position, which will be shifted due to the collision. This means that the amplitude on the side with the wall will be reduced to x, and on the other side, it will be 2A-x, assuming an elastic collision where kinetic energy is conserved, and the mass rebounds with the same speed.
The amplitude of SHM is the maximum displacement from the equilibrium position. An elastic collision is one in which there is no net loss in kinetic energy. In such collisions, the speed of the mass when it returns to the collision point will be the same as it was before, but it will have a new maximum displacement on the other side, resulting in a different amplitude on either side of the mean position post-collision.