The length of minutes hand of a clock is `5 cm` . Calculate its speed.

Options

A. `7.8 xx 10^(-3) cm//s`
B. `7 xx 10^(-3) cm//s`
C. `8.7 xx 10^(-3) cm//s`
D. None

Answer

C

Explanation

Here, ` r = 5 cm , v = ?`
Time taken by minute's hand of a clock to go once around the circle , ` t = 60 min = 60 xx 60s`
From , ` v = ( 2 pi r)/( t) = 2 xx ( 22)/(7) xx (5)/( 60 xx 60) = 8.7 xx 10^(-3) cm//s`