Question

Force acting on the particle moving with constant speed in a straight line path is

• A. Always zero
• B. Need not be zero
• C. Always non zero
• D. Cannot be concluded

Answer 1

The correct option is A

Always zero

1. We know that if $m$ is the mass of a body and $a$ is its acceleration, then the force acting on the body is given as $F=ma$ ……… $\left(1\right)$
2. It is given that the body travels at a constant speed in a straight-line path.
3. This means that the magnitude and direction of the speed of the body are the same throughout.
4. Hence the body can be said to be traveling with a constant velocity.
5. Since there is a constant velocity, the rate of change of velocity, acceleration $a=0$
6. Hence, the force acting on the body $F=0$.

Therefore, the force acting on the particle moving with constant speed in a straight line path is always zero, making option $A$ the correct answer.