# Basic Physics

1. Mar 17, 2004

### Louis Vuiton

I have a simple physics problem that I can't correctly solve. I have a 50g toy bus that is sitting still on a ramp. I need to find the Force needed to keep the bus still on the ramp. How do I do this?

2. Mar 17, 2004

### Severian596

First off you know that as you increase the incline of the ramp, the force needed to hold the bus there also increases. So the angle $$\theta$$ of the ramp is important.

Using $$\theta$$, find the proportion of the force that's Normal (acting perpendicular to the ramp) and the proportion of the force that's parallel to the ramp. The bus's mass is important to calculate this. Start by finding the force Normal on a $$\theta=0$$ incline and go from there.

You'll need a force that's opposite the downward-incline force to keep the bus standing still.

3. Mar 17, 2004

### Michael D. Sewell

1.) Draw it.
2.) Set the x axis parallel to the inclined plane.
3.) The weight W is vertical
4.) The angle between W and the y axis is theta (the same as the angle of the incline).
5.) F = -W sin theta.

I hope I haven't done too much of this for you. Make you sure have a full understanding of this problem before moving on to the next one. -Mike