A 5.0 kg block pushed 3 m up a vertical wall

[Trista]

This 5.0 kg block is pushed 3.0 m up a vertical wall with constant speed by a constant force of magnitude F applied at an angle of theta = 30 degrees with the horizontal. mu kenetic = .30 between wall and block. I need to a). determine the work done by F, b) the force of gravity and c) the normal force between block and wall, and d) by how much does the gravitational potential energy increase during the blocks motion?
I think I figured out the triangle as follows: x element is 2.28, y element (of course) is 3.0 m , and r = 4.56. I'm not even sure if those are correct. In any case, the normal force would be zero because its vertical, right? So, the force of mass X gravity is one force, plus the force applied, and the friction must be taken into account.

Don't I need to solve for the F first, before finding work? I wish this were easier for me! I have more homework than this, and its taking all day!
Thank you for your help!

 

[Fermat]

Find the force F first, yes.

Resolve the force F into horizontal and vertical components.
Since the movement is with constant velocity, that means there is no acceleration therefore no net force. i.e. all the forces must balance.

If you balance the horizontal and vertical forces, you should be able to solve for F.

 

[Trista]

Ok, let's give this a try:
F horiz = n-w sin 60 degrees n= normal force, w = weight (mg)
F vert = mg(mu) m= mass, g= gravity mu = .30
so, I set them equal to each other?
F horz = F vert
Is this the right track? Thank you for helping, I feel like I'm getting really close to understanding this thing.

 

[Fermat]

...
F horiz = n-w sin 60 degrees n= normal force, w = weight (mg)
F vert = mg(mu) m= mass, g= gravity mu = .30
so, I set them equal to each other?
F horz = F vert
Is this the right track? ...

I'm afraid not
That may have been my mistake. When I said

If you balance the horizontal and vertical forces, ...

I didn't mean with each other.

When the horizontal forces, say, balance, that means that they (the horizontal forces) balance with each other. All the forces acting to the right balance (are equal to) all the forces acting to the left.
So,

[tex]\Sigma F_{horiz} = 0[/tex]
[tex]N - Wsin(60) = 0[/tex]

Also,

[tex]\Sigma F_{vert} = 0[/tex]

You need to find all the vertical forces acting on the block. Then balance them. All the upward acting forces are equal to all the downward acting forces.

 

[Trista]

OK, I got it now

Thank you, I think I have it now. I appreciate your help.