Question

Find the distance covered by the minute hand in 10 minutes if its length is 21 cm.
[3 Marks]

Answer 1

We know the minute hand moves in a circular path.
$⟹$Radius = Minute hand length = 21 cm

Angle subtended by minute hand in 5 minutes = $\frac{360°}{12}$ = ${30}^o$
Hence angle subtended in 10 mintues =
= 2$\times$${30}^o$ = ${60}^o$
[2 Marks]
Distance covered by minute hand in 10 minutes
= Length of arc = $\frac{{60}^o}{{360}^o}$$\times$2$\times$pi$\times$r
= $\frac{1}{6}$$\times$2$\times$$\frac{22}{7}$$\times$21 = $\frac{2\times 22\times 21}{6\times 7}$ = 22 cm.

[1 Mark]