Physics : Basic Concepts

Q 16 / 22

UPSC CSE Prelims 1999

A hunter aims his gun at a point between the eyebrows of a monkey sitting on a branch of a tree. Just as he fires, the monkey jumps down. The bullet will:

EXPLANATION

Correct Option

This scenario illustrates the principle of independent motion under gravity. When the hunter fires the bullet and the monkey simultaneously drops from the tree branch, both objects begin to accelerate downwards due to gravity at the same rate (approximately 9.8 m/s²). The horizontal motion of the bullet is independent of its vertical motion. While the bullet travels horizontally towards the monkey, it also falls vertically. Concurrently, the monkey also falls vertically from its initial position. Since both experience the same downward acceleration from gravity, their vertical displacements from their respective initial positions will be identical at any given time. Therefore, if the bullet was aimed directly at the monkey's initial position and the monkey drops at the exact moment the bullet is fired, the bullet will intersect the monkey's path at the point aimed.

Incorrect Options

  • Option (B) is incorrect. Both the bullet and the monkey are subject to the same acceleration due to gravity. Consequently, neither falls faster or slower than the other in the vertical direction.

  • Option (C) is incorrect. As explained for option (B), the vertical motion of both objects is governed solely by gravity, resulting in identical downward acceleration. There is no physical basis for the monkey to fall slower or the bullet to overshoot.

  • Option (D) is incorrect. Based on the principle of independent motion and simultaneous fall under gravity, the bullet will hit the monkey at the aimed point, assuming ideal conditions such as negligible air resistance and precise timing of the shot and drop.

SOURCENCERT Class 9 Science Chapter 10: Gravitation