A force `F=50N` is applied at one end of a string, the other end of which is tied to a block of mass `10kg`. The block is free to move on a frictionless horizontal surface. Take initial instant as `theta=30^@` and final instant as `theta=37^@`. For the time between these two instants, answer teh following questions?

What is the final velocity of the block if initially it was at rest?

Options

A. (a) `sqrt(25/3)ms^-1`
B. (b) `5ms^-1`
C. (c) `sqrt(20/3)ms^-1`
D. (d) None of these

Answer

C

Explanation

`W=1/2m(v^2-u^2)`, `u=0`
`=100/3=1/210v^2=v^2=20/3impliesv=sqrt(20/3)ms^-1`