Question

A stone tied at the end of a string 80 cm long is whirled in a horizontal circle with a constant speed. If the stone makes 25 revolutions in 14 s, what is the magnitude of acceleration of the stone ?

Answer 1

Length of string =80cm=0.8m

Stone makes 25 revolutions in 14s

Hence, stone makes 25/14 revolution in 1sec

e.g frequency =1425sec−1

We know,

Angular speed (w) =2π×frequency

                                =2π×1425

                                =725π rad/sec

Now, acceleration (a) =w2r

where, r is the radius (length of string)

Acceleration =0.8×(725π)2

                      =0.8×(778.5)2

                      =100.60m/s2