# Acclerating plane

1. Jul 15, 2005

### huskydc

this is another post, but i just want to post it in this room and see if ANYONE knows how to solve this:
I've tried everything, now i'm getting depererate

An inclined plane that makes an angle of 28° to the horizontal is mounted on wheels. A small block of mass m = 1.2 kg rests on the plane, held there by a coefficient of static friction µ = 0.73.

The plane is accelerating to the right. What is the minimum acceleration in order that the block slides down the plane?

Any help would be great !!!!!

2. Jul 15, 2005

### Pyrrhus

Apply Newton's 2nd Law and solve for a.

The 0 degrees with the horizontal system of coordinates will be the easier one.

3. Jul 15, 2005

### huskydc

i came up with the following, after lots of equation, i used it to solve for a, didn't work either

g sin (theta) - mu (a sin (theta) + g cos (theta) ) = a cos (theta)

4. Jul 15, 2005

### Pyrrhus

Well, with the coordinate system set as i said above.

$$\sum F_{x} = ma = - n \sin \theta + F_{f} \cos \theta$$

$$\sum F_{y} = 0 = F_{friction} \sin \theta + n \cos \theta - mg$$

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Last edited: Jul 15, 2005