PHYSICS HELP!!please!?

Question

A 90.0-N box is pulled 10.0 m along a level surface by a rope. If the rope makes an angle of 20.0° with the surface, and the force exerted through the rope is 75.0 N, how much work is done on the box?

Please help I don't understand how to do this question.

Answer 1

Start off by making the force go parallel to the surface. In order to do this Multiply the 75 Newton force by cos(20.0)

Now that you have the force parallel to the level surface use the Work equation W=Fd.

W= 75*cos(20)*10m

Now you must subtract the force of friction from this which is equal to the normal force: 90 N * 9.8

Hope that helps

Answer 2

Assuming no friction, you would have to just take 75N and figure out how much is horizontal force and how much is vertical force.  To do that, you'll take 75 * ( cos(20) ), making sure your calculator is in degree mode, to come up with your horizontal force, and 75 * ( sin(20) ), to come up with your vertical force.

Work is equal to force times distance, right?  So now that you have your force, multiply that by your distance and you have the amout of work done on the box.