# Homework Help: 3 children and a balancing a seesaw

1. Dec 4, 2008

### Bones

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

Three children are trying to balance on a seesaw, which includes a fulcrum rock acting as a pivot at the center (x = 0), and a very light board 5.2 m long (see figure). Two playmates are already on either end. Boy A has a mass of 50 kg, and boy B a mass of 35 kg. Where should girl C, whose mass is 25 kg, place herself so as to balance the seesaw?

http://www.webassign.net/gianpse4/12-57.gif

2. Relevant equations

3. The attempt at a solution

(45kg)(9.8m/s^2)(-2.6m)-(35kg)(9.8m/s^2)(2.6m)+(25kg)(9.8m/s^2)(x)
-1146.6N*m-891.8N*m+245N(x)
-2038.4N*m=-245N(x)

2. Dec 4, 2008

### LowlyPion

First of all skip putting the value of g. It cancels out.

Second of all put in the correct masses. 50 and 35.

Finally put the 35kg and 25 kg kids on the same sides and equal to the side with the 50 kg kid.

3. Dec 4, 2008

### Bones

Thanks, that helped a lot. I didn't realize the picture did not match up with the problem. No wonder I was not getting the correct numbers.

4. Dec 5, 2008

### LowlyPion

Measure twice and then cut once.