Question

If a body is moving at constant speed in a circular path, its:

• A. velocity is constant and its acceleration is zero
• B. velocity and acceleration are both changing direction only
• C. velocity and acceleration are both increasing
• D. velocity is constant and acceleration is changing direction

Hint:

In uniform circular motion:

Speed = constant
Velocity = changing direction
Acceleration = centripetal, always towards the centre

Answer 1

The Correct Option is B

Step 1: Recall the concepts of speed and velocity.

Speed is a scalar quantity (magnitude only).
Velocity is a vector quantity (magnitude and direction).
Step 2: Analyze motion in a circular path. When a body moves in a circular path at constant speed:

The magnitude of velocity remains constant.
The direction of velocity keeps changing at every point.
Step 3: Understand acceleration in circular motion. There is always a centripetal acceleration directed towards the centre of the circle.

Its magnitude remains constant (if speed and radius are constant).
Its direction keeps changing as the body moves along the circle.
Step 4: Evaluate the options.

(A) Incorrect — velocity is not constant
(B) Correct — both velocity and acceleration change direction ✔
(C) Incorrect — neither increases
(D) Incorrect — velocity direction also changes
Step 5: Final conclusion. The correct answer is \(\boxed{\text{(B)}}\).