# Homework Help: Towing A Car

1. Nov 5, 2004

### pitchharmonics

What varibles might be need to find the force necessary to pull a car on to a tow truck at an angle?

Last edited: Nov 5, 2004
2. Nov 5, 2004

### BobG

There are a few variables to take into consideration if you're talking about the car starting from a dead stop and accelerating to a constant speed, the force necessary to pull the car up the ramp, etc., but if you only need the constant speed of the car up the hill, the problem is fairly simple.

The force from the tow truck has to match the force that gravity is pulling the car down the hill with. You need to take the inclination of the hill into consideration to figure out how much of gravity's force is directed directly along the road, down the hill. That's a trig problem.

One other possible variable is the angle of the cable relative to the car. The simplest problem has the cable nearly horizontal so you don't have to figure out how much force from the machine is actually applied to pulling the car along the road (that's another trig problem).

The only other possible variable is the coefficient of friction, which, if given, will resist both the motion of the car down the hill and the motion up the hill. My guess is that they avoided tossing the coefficient of friction in by using a car. A rolling wheel doesn't have a very high coefficient of friction. If it is given, just remember that it will resist the force of the tow truck and has to be added to the force necessary to balance the force of gravity.

3. Nov 5, 2004

### pitchharmonics

Thank You BobG