# Homework Help: Body Diagram

1. Mar 14, 2013

### Toranc3

1. The problem statement, all variables and given/known data

Two horses pull horizontally on ropes attached to a stump. The two forces F1= 1300 N and F2 that they apply to the stump are such that the net (resultant) force R has a magnitude equal to that of F1 and makes an angle of 90 with F1.

What is the magnitude of F2?

2. Relevant equations

3. The attempt at a solution

I got the answer correct but I was confused with the wording. F2 ended up being at some angle with respect to the x-axis and F1. I thought that this force was horizontal. Could somebody clarify this? Also could this be solved using the dot product?

θ=135
F2= 1838N

2. Mar 14, 2013

### Staff: Mentor

When they say that the horses pulled horizontally, they just mean that the ropes were parallel to the ground, not angling upward or downward.

If F1 is along the y-axis, then the resultant will be along the x-axis. You use that fact to solve for F2. (The x-y plane is the plane of the ground.)

How did you solve it?

3. Mar 14, 2013

### Toranc3

Fy:

F=ma

ma=R
F2sin(theta) =1300N

Fx:

F=ma
F1+F2cos(theta) =ma

ma=0

-F1/cos(θ) =F2

I substituted this into the Fy. I am not sure if this is the correct way to do it though.

4. Mar 14, 2013