Question

A car runs at a constant speed on a circular track of radius $100\, m$, taking $62.8\, s$ for every circular lap. The average velocity and average speed for each circular lap respectively is

• A. 0 , 0
• B. 0 , 10 $ms^{-1}$
• C. 10 $ms^{-1}$ , 10 $ms^{-1}$
• D. 10 $ms^{-1}$ , 0

Answer 1

Answer: (B)

On a circular path in completing one turn, the distance travelled is $2\pi r$ while displacement is zero.
Hence, average velocity = $\frac{displacement}{time - interval} = \frac{0}{t} = 0$
Average speed = $\frac{Distance}{Time -interval}$
= $\frac{2\pi r}{t} = \frac{2 \times 3.14 \times 100}{62.8} = 10 \,ms^{-1}$