Work and Power Questions NEED Help

[Turnips]

1. A 50kg crate is pulled 40m along a horizontal floor by a constant force exerted by a person, Fp=100N, which acts at a 37 degree angle. The floor is rough and exerts a friction force Ff= 50N. Determine the work done by each force acting on the crate (including normal force and force of weight), and the net work done on the crate.



W=F*d*cos( angle )

3. no idea how to do it.

 

[rock.freak667]

What is the magnitude of the component of Fp acting in the direction of motion?

 

[Turnips]

Im guessing its just 100N because that's all the problem gives me.

 

[rock.freak667]

Are you familiar with http://www.glenbrook.k12.il.us/gbssci/phys/Class/vectors/u3l3b.html ?

 

[Turnips]

Yes.

 

[rock.freak667]

Then resolve the 100N acting at 37 degrees into horizontal and vertical components.

 

[Turnips]

The Fy = 60.18N and the Fx = 79.86N

 

[rock.freak667]

The Fy = 60.18N and the Fx = 79.86N

Good.

Now what would be the work done in moving the crate 40 m in the direction of Fx? and in the same manner what is the work done by the frictional force?

 

[Turnips]

79.86N * 40 m = 3194.4J is the Work done in the x Direction
50N * 40m = 2000J is the work done by Friction

 

[rock.freak667]

79.86N * 40 m = 3194.4J is the Work done in the x Direction
50N * 40m = 2000J is the work done by Friction

That is what the question asks for.

Now vertically. Is the crate moving either up or down? If so then some force is doing work on it. If not then no work is done on the crate

 

[Turnips]

Alright thanks very much.