Question

A body is imparted motion from rest to move in a straight line. If it is then obstructed by an opposite force, then

• A. The body may necessarily change direction
• B. The body is sure to slow down
• C. The body will necessarily continue to move in the same direction at the same speed
• D. None

Answer 1

The correct option is B

The body is sure to slow down

The explanation for the correct option(s):

Option B: The body is sure to slow down

1. The direction of the opposing force is opposite to the direction of motion, this will cause retardation.
2. So the body will slow down because of the opposing force.

Explanation for the incorrect option(s):

Option A: The body may necessarily change direction

1. Due to opposite forces, the velocity of the body will decrease but we can not say anything about its direction.
2. As if force is applied opposite with an angle, then it will slow down the object as well as change the direction.
3. If force is just the opposite, then velocity will change but not the direction.

Option C: The body will necessarily continue to move in the same direction at the same speed

1. The force may be acting at right angles to the motion of the body, neither accelerating it nor decelerating it, but constantly changing its direction of motion, and constraining it to move in a circle.

Hence, option B is correct.