Question

The minute hand of a clock is 10 cm long. How far does the tip of the hand move in 20 minutes

• A. $\frac{10\pi}{3}$
• B. $\frac{20\pi}{3}$
• C. $\frac{30\pi}{3}$
• D. $\frac{40\pi}{3}$

Answer 1

Answer: (B)

$\frac{20\pi}{3}$

Answer 2

We know that the tip of the minute hand makes one complete round in one hour i.e. 60 minutes since the length of the hand is 10 cm. the distance moved by its tip in 60 minutes $= 2\pi \times 10cm = 20\pi cm$

Hence the distance in 20 minutes $= \frac{20\pi}{60} \times 20cm = \frac{20\pi}{3}cm$.