- #1

virtuoso735

- 6

- 0

## Homework Statement

[PLAIN]http://img849.imageshack.us/img849/3716/staticeqpulley.jpg

Hopefully the image showed up. If not, here's the link: http://img707.imageshack.us/img707/3716/staticeqpulley.jpg"

Sorry for the low quality pictures. Hopefully it will do though. The question is: Relate the traction force F

_{3}to the weight

*mg*and the angle theta.

## Homework Equations

They give us that the tension T is uniform throughout the string (i.e. F

_{1}, F

_{2}= T). F

_{3}acts along the horizontal.

## The Attempt at a Solution

I resolved the diagonal forces into horizontal and vertical components. Since θ

_{1}and θ

_{2}are equal I just call them both θ. The system is in static equilibrium so the total force is zero. So I expand the equilibrium equations out as follows:

-F

_{1}cosθ - F

_{2}cosθ + F

_{3}= 0

and

-F

_{1}sinθ + F

_{2}sinθ = 0

Also, T = mg

Do I just sum the two equations above and set them equal to

*mg*? That doesn't make sense since the sum is 0, and

*mg*is certainly not 0. Or should I sum them and subtract

*mg*from the sum?

Any help would be appreciated! Thanks.

Last edited by a moderator: