A block is moved from rest through a distance at `4 m` along a string line path . The mass of the block is `5 kg` and the force acting on it is `20N`. If the kinetic energy acquired by the block be `40 J`, at what angle to the path is the force acting?

Options

A. `30^(@)`
B. `45^(@)`
C. `60^(@)`
D. None of these

Explanation

Let required angle is `theta`
Work done = change in `KE`
` implies Fs cos theta = 40 - 0`
`implies 20 xx 40 cos theta - 400 implies theta = 60^(@)`