a box with weight 50 n slides down on an incline plane for a distance of 5m with constant velocity . if the angle between the plane and the horizontal is 30 degree what is the work done by the force of gravity ?

Question

anonymous · Answer

do you knw how to calculate work done by a force?

anonymous · Answer

work done . force X distance right ?

anonymous · Answer

that is only the case if the force and distance are in the same direction

what happens if the force and the displacement are not in the same direction? if they make some angle ?

anonymous · Answer

i dont sure  . still confused . how to ans question like that ?

anonymous · Answer

well let me help you with an example

look at this drawing!!

|dw:1376324505559:dw|
in this case u see that, they make an angle.. you come up with such cases in your real life.. for example this may be when you are cleaning the floor with a vacuum cleaner or a mop.. when you pull the cleaner/or the mop, you pull at an angle.. and so force and displacement make angles with each other.. 

in this case its not fair to say that the entire force is doing work.. so we resolve this force into two components
one along the displacement
another perpendicular to the displacement ..