Question

A body covers a semicircle of radius 7 cm in 5 seconds find its linear speed

Answer 1

We can do this by,

V(linear speed)= 2*22/7*r/t
= 2*22/7*7/5
= 1/55
=0.018m/s Answer

Answer 2

The radius of the semi circle [r] = 7 cm i.e 0.07 m

The time taken by the body to cover the semi circle [t] = 5 seconds.

The angular displacement of the particle for half rotation $[\theta]= \pi$ rad.

The angular velocity $\omega=\frac{\theta}{t}$

                                         $=\frac{\pi}{5}\ rad/s$

The linear speed is calculated as follows-

                                 $linera\ speed\ v=r\omega$

                                                     $=0.07\ m*\frac{\pi}{5}\ cm/s$

                                                     $=0.04398\ m/s$

                                                     $=4.398*10^{-2}\ m/s$  

Hence, the linear speed of the body is  $4.398*10^{-2}\ m/s$