Question

A ball thrown vertically upwards after reaching a maximum height h returns to the starting point after a time of 10 s. Its displacement is
A. h
B. 2 h
C. 10 h
D. zero

Answer 1

Hint: Displacement is the measure of how much a body is displaced from its initial position or starting point. Displacement does not depend on a path covered by the body but depends on the initial and final point of the object. Displacement is equal to the shortest distance between the initial and final positions. In this question, we need to find the displacement of the ball which is projected straight upward from the ground and after 10 seconds it returns to its initial state.


Complete step by step solution:
When a body covers a complicated distance from point A (home) to B (school), instead of going straight from A to B but covering another path C, in that case, displacement of the body does not consider the complicated path but the shortest distance from point A to B and can say depend on initial and final point like AB.

Now, as a ball is thrown from the ground (initial position) straight upward and it reached to maximum distance so, we can say the body is displaced from the initial to that maximum distance but in this question, we need to find displacement when body after reaching maximum height return back after 10 sec to the same position.

So, in that case, the initial and final position of the ball is the same so if we substrate the initial position from the final position (final position – initial position) then we find the null result. In that case, we can say no displacement has taken place or the ball has not displaced from its position.

Thus, the correct option D.

Note: In one place, where displacement does not depend on the path but only on the final and initial position, distance is the one that measures the whole path and does not depend on the final and initial position. The displacement of the pendulum is also zero because after covering the maximum height from mean position, bob of the pendulum comes to the same mean position (initial position) from where it started to oscillate.