How do inclined planes affect forces on an object?

[man0005]

Homework Statement

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Homework Equations

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The Attempt at a Solution

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[PhanthomJay]

Some of these are correct and others are not. Please show how or why you arrived at your answers.

 

[man0005]

1) Not sliding = Friction present
2) W is hypotenuse, so must be larger than N
3)a) hmm I think might be Equal at a second glance? since its at rest
b) n = W cos angle
logically should increase?
4a) yeah that should be equal as well i think, since at rest. sorry ==
b) constant velocity = 0
so a = 0
and f = 0?
If the angle changes wouldn't it not move at constant velocity anymore? so acceleration would occur?
c) hmm not sure about this one. i just answered using logic. steeper = move faster?
and the vertical one should just be g shouldn't it?

 

[L2E]

I'll give you some things to think about
1) friction acts to reduce movement, if an object isn't moving or if nothing is trying to move it, then does friction act against that?
2)sounds good
3)a) if it is at rest, all of the forces will add up to 0
b)for 0<angle<90, cos(angle) decreases
4a)see 3a)
b)there is still friction, just that the friction + normal force + weight = 0 however the block moves.
increase angle: N is reduced, therefore F is reduced, W stays the same
will the forces still be balanced?
5)When the incline is vertical, what is N? and therefore, what is F?

 

[man0005]

1) oh! yeahh, there isn't any friction acting whoops
3a) yeah so if its adds to zero, must be same magnitude but diff direction right?
b) oh yeah zzzz, so magnitude would decrease yeah?
4b) why would F decrease with an increase of angle? either way forces would become unbalanced, so I am right yeah?
5) How do you determine F from N O_O