A block of mass `M` is hanging over a smooth and light pulley by a constant force `F`. The kinetic energy of the block increases by 20 J in 1 s.

Options

A. The tension in the string is Mg.
B. The tenstion in the spring is F.
C. The work done by the tenstion on the block is 20 J in the above 1 s.
D. The work done by the force of gravity is 20 J in the above 1 s.

Answer

B

Explanation

`T=F`
Net work done `=20J`
`(T-Mg)`(displacement)`=20`
`(F-Mg)`(displacement)`=20`