math word problem?

What you basically need to do is find the force trying to pull the truck down the hill. The force required to counter is (from newton's law) the equal, opposite force, since this is a static problem (aka. nothing is moving at the moment.)

Draw a diagram of the truck. Gravity acts straight downward on it, but because it is at an angle, part of the gravity pulls it down the hill. Using some geometry you can split the force of gravity into components. An x direction component and a y direction component. Notice the coordinate system I've imposed on the truck with the x direction parallel to the hill.

I tried to do a drawing of it for you. Go here to see it:

http://i75.photobucket.com/albums/i288/fearispink/...

That should make this make a little more sense....hopefully.

Anyway, you need to find the force directed down the hill (parallel to it). That's the Wsin(theta) in the picture.

So find that force:

First convert 22 tons to lbs:

22*2000 = 44000 lb.

Wsin(theta) = 44000*sin(20) = 15049 lb.

Now this force and the force required to counter it are both along the "x" axis. so sum the forces in the x direction using Newtons law for static problems (remember to pay attention to signs. I've chosen towards the bottom right corner to be the positive x direction.):

Sum of the forces in the x direction = 0

sum x forces = wsin(theta) - counter force = 0

counter force = w sin(theta)

counter force = 15049 lb.

(Edit: I noticed that someone else answered and used acceleration due to gravity, but this is not necessary.

In the problem, you're given a measurement of Weight. This weight is measured in tons or pounds after a simple conversion and both tons and pounds are units of force.

The reason you sometimes need acceleration due to gravity (g) in a problem is because they give you only the mass of the object. Because force equals mass times acceleration, you need to take that mass and multiply it by g in order to get a weight force. But in this problem they already give you a weight, and it's in units of force, so you don't need to worry about converting it to force.

If they had given you 22 slugs instead of tons, then you would have had to multiplied by the english system g, which is 32.2 ft/s^2.)

22txgravity force=22000x9.8=215600

215600x cos 70 =215600x0.34= 73739.5

this is the force required to stop the truck from rolling

We have not considered the friction forces

22000*9.81*cos 20