Problem 69 - A Complete Resource Book in Physics for JEE Main

Question

A ball is travelling with uniform translatory motion. This means that (A) it is at rest. (B) the path can be a straight line or circular and the ball travels with uniform speed. (C) all parts of the ball have the same velocity (magnitude and direction) and the velocity is constant. (D) the centre of the ball moves with constant velocity and the ball spins about its centre uniformly.

Step-by-Step Solution

Answer

The correct answer is (C) all parts of the ball have the same velocity (magnitude and direction) and the velocity is constant, as it accurately describes uniform translatory motion.

Step 1: (A) it is at rest.

In uniform translatory motion, the ball isn't at rest because it has a constant velocity. So, statement (A) is incorrect.

Step 2: (B) the path can be a straight line or circular and the ball travels with uniform speed.

Although the ball travels with a uniform speed, the path of the motion in uniform translatory motion should be a straight line, not a circle. Thus, statement (B) is incorrect.

Step 3: (C) all parts of the ball have the same velocity (magnitude and direction) and the velocity is constant.

This statement fits the definition of uniform translatory motion: all parts of the object move with the same constant velocity (magnitude and direction). Statement (C) is correct.

Step 4: (D) the centre of the ball moves with constant velocity and the ball spins about its centre uniformly.

Focusing on the spinning of the ball around its center is not relevant for uniform translatory motion. We are only concerned with the constant velocity of all parts of the object. So, statement (D) is incorrect. From the analysis of each statement, we can conclude that the correct answer is (C) all parts of the ball have the same velocity (magnitude and direction) and the velocity is constant.