Work on an Incline: Calculating Force and Work

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A 60-kg crate is slid up an inclined ramp 2.0-m long onto a platform 1.0m above the floor level. A 400-N forcem, parallel to the ramp, is needed to slide the crate up the ramp at a constant speed.
a) How much work is done in sliding the crate up the ramp?
b) How much work would be done if the crate were simply lifted straight up from the floor to the platform?

I believe I use W = F*D, but is the distance equal to the hypotenues of the ramp?

And how come you can't just do W = (400)*(1.0) for the second question?

Help please

 

[Doc Al]

I believe I use W = F*D, but is the distance equal to the hypotenues of the ramp?

Right. The applied force is parallel to the ramp and the distance the crate moves in that direction is given as 2.0 m. The work done by a force equals Force x Distance in the direction of the force.

And how come you can't just do W = (400)*(1.0) for the second question?

In the second problem the 400 N force doesn't exist. The force needed to lift the crate equals the weight of the crate and points upward. The upward distance the crate is moved is 1.0 m.

 

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So its 400*2.0?

And for the second part is it m*g*1.0m?

 

[Doc Al]

Right! Be sure to give the proper units when you present your answers.

 

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Awsome, thanks!