Bracket/block static friction problem (physics)

[notbynumber]

Homework Statement

http://img3.imageshack.us/img3/6618/5n6.jpg
Image there.

Homework Equations

Well this is actually where the problem occurs. You make your own equations.

The Attempt at a Solution

It's the friction that is really messing me up. I'm just so confused, I'm going to show you my attempt at FBDs for the problem.

I think that if I just know how to draw them correctly I'll be able to find my answer, unless there is some other tricky way to get it.

Okay so for the 12kg block, we have:

m1g going DOWN
n1 going UP
T to the LEFT
fs to the LEFT

And for the 7kg bracket, we have:

m2g going DOWN
n2 going UP
n1 going DOWN
T to the RIGHT?
fs to the RIGHT

Apparently I didn't draw them correctly because when I try to solve for something, there are always two variables... other than f = Mu*N which equals 94.08 N.

 

[notbynumber]

Did I mention this is due soon? Please everyone, I really need your help.

 

[tomcue]

I understand your frustration with this problem. It can be challenging to draw accurate free body diagrams and determine the appropriate equations to use in solving a physics problem. However, it is important to remember that practice and perseverance are key in mastering these skills.

In this case, you have correctly identified the forces acting on each object in the system. However, there are a few things to note. First, the normal force between the 7kg bracket and the 12kg block is actually n1, not n2. This is because the two objects are in contact with each other, so they share a normal force. Additionally, the tension force T should be pointing in the same direction for both objects, since they are connected by the rope.

To solve for the unknowns in this problem, you can use the equations for static friction and Newton's second law. For the 12kg block, the equation would be:

ΣF = ma
T - fs = m1g

For the 7kg bracket, the equation would be:

ΣF = ma
fs - T = m2g

You can use these equations to solve for the unknowns fs and T. Additionally, you can use the fact that the two objects are connected by a rope to set up a system of equations and solve for both unknowns simultaneously.

I hope this helps you in your problem-solving process. Remember to always double check your free body diagrams and equations, and don't be afraid to ask for help if you get stuck. Good luck!