The length of a seconds hand in watch is `1 cm.` The change in velocity of its tip in `15 s` is

Options

A. zero
B. `pi/(30 sqrt2) cm//s`
C. `pi/30 cm//s`
D. `(pi(sqrt2))/30 cm//s`

Answer

D

Explanation

`v=(2piR)/T=((2pi)(1))/60=(pi/30)cm//s`
In 15s, velocity vector (of same magnitude ) will
rorate `90^@.`
`:. |Deltav|=|v_f-v_i|=sqrt(v^2+v^2-2v vcos 90^@)`
`=sqrt2 v=(pisqrt2)/30 cm//s`