Question

Assertion - A body can have acceleration even its speed is constant.

Reason - In uniform circular motion, speed of body is constant but its velocity continuously

changes.

Answer 1

Answer: Both (A) & (R) are correct and (R) is the correct explanation of (A).

Explanation: Speed is a scalar quantity. Meaning, it has only magnitude. It doesn't specify direction. But in uniform circular motion, direction of particles changes gradually keeping magnitude of velocity constant. Therefore, there is a change is velocity. And where there is a change, there is an acceleration.

Answer 2

The assertion (A) and Reason (R) are true and the reason is a correct explanation to assertion.

• A body can have acceleration even if its speed is constant. This is due to the change in direction of the particle. Acceleration is the rate of change of velocity.
• Velocity is a vector quantity and has both magnitude and direction. Even if speed is constant there can be change in direction of particles which will contribute to acceleration.
• In a uniform circular motion, speed is constant, but the body still has acceleration, because at every point the direction of particle changes.
• Therefore, both assertion and reason are true, and the reason is the correct explanation to assertion.