# Homework Help: Force problem:

1. Jun 4, 2007

### Zeth

I'm not looking for an answer, I was just wondering who was right:

In a tug-of-war, a jeep of mass 1400 kg and a tractor of mass 2000 kg pull on a horizontal rope in opposite directions. At one instant, the tractor pulls on the rope with a force of 1.50 × 10^4 N, while its wheels push horizontally against the ground with a force of 1.60 × 10^4 N. Calculate the accelerations of the jeep and the tractor, and the horizontal force of the wheels of the jeep on the ground.

Now the way I see it the force is the difference of the force on the wheels of the tractor and the ground, which is 1000N. But the mark scheme says that the acceleration due to that is just the weight of the tractor/1000 but I figure it should be the weight of the tractor plus the weight of the jeep/1000 since the rope is taught. Am I right?

2. Jun 4, 2007

### Zeth

Bump, anyone?

3. Jun 4, 2007

### Staff: Mentor

No, you are not right. You found the net force on the tractor; thus you would apply Newton's 2nd law to the tractor to find its acceleration. You'd use the mass of the tractor alone.

If you had the net force on the entire system of jeep+tractor, then you'd be able to find the acceleration of the system using the total mass.