The length of second's hand in watch is `1 cm`. The change in Velocity of its tip in 15 seconds is

Options

A. Zero
B. `pi//30 cm//s`
C. `(pi//30) sqrt(2) cm//s`
D. `pi//30 sqrt(2) cm//s`

Answer

C

Explanation

Angular velocity of second hand ,
`omega = (2 pi)/(60) = (pi)/(30) rad//s`
`Delta vec(v) = vec(v_(2)) - vec(v_(1)) = vec(v_(2)) + (- vec(v_(1)))`
`Delta v = |Delta vec(v)| = sqrt(2) r omega = sqrt(2) xx 1 xx (pi)/(30)`
`= (sqrt(2) pi)/(30) cm//s`