Question

A cyclist moving on a circular track of radius 40 m completes half a revolution in 40 s. Its average velocity is:

• A. zero
• B. \(4\pi \, \text{m/s}\)
• C. \(2 \, \text{m/s}\)
• D. \(8\pi \, \text{m/s}\)

Hint:

Average velocity depends on displacement, not distance. In circular motion, always check the net displacement.

Answer 1

The Correct Option is C

Concept: Average velocity = Displacement / Time. For circular motion, displacement is the straight-line distance between initial and final positions.

Step 1: Displacement in half revolution.
After half revolution, the cyclist reaches the opposite point of the circle. \[ \text{Displacement} = \text{diameter} = 2R = 2 \times 40 = 80 \, \text{m} \]

Step 2: Average velocity.
\[ v_{avg} = \frac{\text{Displacement}}{\text{Time}} = \frac{80}{40} = 2 \, \text{m/s} \]