# Homework Help: A block slides down an inclined plane of slope angle (theta)

1. Feb 7, 2014

### PHYSStudent098

1. The problem statement, all variables and given/known data

A block slides down an inclined plane of slope angle (theta) with constant velocity. It is then projected up the same plane with an initial speed v(knot).

(a) How far up the incline will it move before coming to rest?

(b) Will it slide down again?

2. Relevant equations

I do not know.

3. The attempt at a solution

I do not know where to start. Apologies.

2. Feb 7, 2014

### Staff: Mentor

Determine the co-efficient of friction. Express it in terms of theta.

3. Feb 7, 2014

### lendav_rott

Think about rolling a marble up and down an inclined surface. When you push the marble you exert some certain amount of force on it. That will determine how far it will roll - the friction coefficients will be very different, however the idea is the same.

Whether or not the object will slide down depends how high it managed to get with the initial velocity it was given. If the resulting force acting on the block is great enough to overcome the friction when it stands still, then it will start sliding, if not, it will stay put.

Since we have not been told if this is a 3d or a 2d world - I will assume the simpler 2d world.

Before you start, think about the assignment's first sentence. A block slides down an inclined plane of slope angle (theta) with constant velocity. What does Newton say about this? If the sum of all the forces acting on an object is 0 then the object either doesn't move or moves in one specific direction with a constant velocity.

Gravity's pull down the slope and kinetic friction are equal, this gives you the friction co-efficient.