2 masses connected by a pulley, one on an inclined plane.

[th3dalton]

Homework Statement

A mass m2 = 1.9 kg, on a 34.1° incline, is connected to a mass m1 = 6.2 kg, on a horizontal surface. The surfaces and the pulley are frictionless. If F = 21.8 N, what is the magnitude of the tension in the connecting cord? Link to photo - http://i48.tinypic.com/e0l5hk.jpg

Homework Equations

Fnet = ma

The Attempt at a Solution

I've gotten the answer wrong 9 different times so far and I have no clue why. This is my last attempt(ten tries total).

I've drawn the free body diagrams for both masses, m1 has a positive tension, the force of gravity, and a normal force.
m2 has a normal force perpendicular to the plane which i think equals Fn = (Fg)cos(34.1). It also has a negative tension which is equal to the other tension on mass two, it has the force F pulling along the x axis. So this is what I have no far

Box 1 Fnet = T1
Box 2 Fnet = (21.8N - (fg)sin34.1) i + (fgcos34.1)j

i have all this information, but i have no clue what to do with it. I've tried dividing the (21.8N - fg(sin34.1) by the total weight, which should give me the Fx acceleration, then multiplying that by the 6.2kg mass to give the tension in the connecting cord but that doesn't seem to work.

Like I said, this is my last chance to get the problem right so thanks for any help.

 

[anathema]

Thank you for your post. It seems like you have a good understanding of the problem and have correctly identified the forces acting on each mass. However, your approach to finding the tension in the connecting cord may be a bit off.

To find the tension, you will need to use the equation Fnet = ma for each mass. For mass 1, the only force acting on it is the tension in the connecting cord, so you can set Fnet equal to T1. For mass 2, you will need to break the force of gravity into its x and y components (as you have done) and then use the equation Fnet = ma to find the acceleration in the x direction. This acceleration will be the same for both masses since they are connected by the same cord.

Once you have found the acceleration in the x direction, you can use it in the equation Fnet = ma for mass 1 to solve for the tension in the connecting cord. Remember to use the total mass of both masses (m1 + m2) in this equation.

I hope this helps and good luck with your final attempt! Keep in mind that sometimes it takes a few tries to get the right answer, but don't get discouraged. Keep practicing and you will get it eventually.