A body is executing simple harmonic motion with an angular frequency s rad/2 . The velocity of the body at 20 mm displacement, when the amplitude of motion is 60 mm , is

Options

A. 40 mm/s
B. 60 mm/s
C. 113 mm/s
D. 120 mm/s

Answer

C

Explanation

`v=omegasqrt(A^(2)-x^(2))`
`=omegasqrt((A+x)(A-x))`
`=omegasqrt(80xx40)=2xxsqrt(3200)=80sqrt(2)`
`=113mm//s`