Work is said to be done by a force acting on a body, provided the body is displaced actually in ay direction except in a direction perpendicular to the direction of the force. Mathmatically, `W=vec(F). vec(c)=Fs cos theta`, Whereas eenrgy is capacity of a body to do the work, power is the rate at which the body can do the work.
`P=(W)/(t)=vec(F).(vec(s))/(t)=vec(F). vec(upsilon)`
Both, work and energy are measured in joule and power is measured in watt.
With the help of the comprehension given above, choose the most appropriate alternative for each of the following question `:`
In the above question, work done by gravity is

Options

A. `400 J`
B. `-400 J`
C. zero
D. `-25 J`

Answer

C

Explanation

As motion is along horizontal and gravity is along the vertical, therefore, work done by gravity is
`W=F s cos 90^(@)=Zero`