How Do You Calculate the Forces in Support Braces at Different Angles?

[John Muller]

Homework Statement

A 100 kg box is to be held up by two support braces attached to a wall. One of the support braces makes a 27 degree angle with the wall and the other brace makes a 65 degree angle with the wall. Find the force in each of the support braces that will hold the box up.

Variables:
Possibly T1 and T2 for the support braces, Fg for gravitational force

Homework Equations

F=ma
Trig equations
Fg=M*9.8

The Attempt at a Solution

I have tried to set it up like most of the other equilibrium problems I have, but I ran into a few problems while doing it. Wehn setting up Fnet of the Y values to 0, I do not think I had the right set up. I have F1*cos(65)+((9.8*100)/sin63) -9.8*100=0 I kept on getting a negative for F1 and this did not make sense to me. I can only assume this is happening because I set it up wrong.

 

[Isaac0427]

First off let’s do this symbolically. Instead of 9.8 m/s² let’s say g and m instead of 100 kg.

Second, I have no idea where you are getting that second term in your T₁ equation. Remember, you have two unknowns, T₁ and T₂, so you need two equations. Set up your equilibrium equations and then we’ll go from there.

Also, if possible, to make things easier to understand, can you either use LaTeX or our subscript feature on PF? (it is on the blue panel right above where you write a post)

 

[kuruman]

F1*cos(65)+((9.8*100)/sin63) -9.8*100=0

Why is there no F2 in this equation?