# Homework Help: Tractor force physics

1. Jan 15, 2006

### balletprincess34

two tractors pull against a 1750kg. if the angle of the tractors' chains in relation to each other is 36.0 degrees and each tractor pulls with a force of 8000N what is the total force exerted by the tractors

2. Jan 15, 2006

### andrewchang

yes, approximately.

3. Jan 15, 2006

### balletprincess34

thank u...i just wanted to double check :)

4. Jan 15, 2006

### Ouabache

I am curious, how did you arrive at this answer?

5. Jan 15, 2006

### balletprincess34

process of elimination, law of cosines, formula for calculating force weight...etc etc...

6. Jan 15, 2006

### andrewchang

there was a fair amount of guessing about the question, but I think that it was asking what the resulting force on the object is. Then, if the tractors are pulling at a 36 degree angle from each other, they are pulling at a 18 degree angle from the horizontal (_assuming_ that they are aligned around the horizontal) From then, I just added the vectors. At least, I think that's what the question is asking.

7. Jan 16, 2006

### Ouabache

Hmmmm, not sure how you derived 15,200N using those methods. Perhaps you can explain?

8. Jan 16, 2006

### Ouabache

In my interpretation of the question, I sense, if the tractor chains are pulling at 36 deg angle from each other, then they are each 18 deg from the vertical, meaning they are 72 deg from the horizontal.
Since you are only determining the total force exerted by the tractors (and ignoring the force exerted by gravity on the object with mass 1750kg), you can calculate the horizontal and vertical force components for each chain. The horizontal forces are equal and opposite in direction, so therefore cancel. That leaves the vertical component for each chain.

Just calculate one of them (Fy) and multiply by 2.
(Assuming that both tractors are taller than the mass their chains are attached to) Fy(total) = 2*(8000sin72) = 15217N in upward direction.

If you do take into account the vertical force of gravity on the 1750kg object, then what would be the total resultant force of the system? and in what direction?

Last edited: Jan 17, 2006