# Homework Help: Newton's Laws of Motion

1. Sep 21, 2010

### jessicax07

1. The problem statement, all variables and given/known data
T
here are 2 blocks connected by a string, as shown in the first image attached. The smooth inclined surface makes an angle of 40 degrees with the horizontal, and the block on the incline has a mass m1 = 7.9kg. What is the mass of the hanging block m2 that will cause the system to be in equilibrium.

2. Relevant equations

$$\sum$$F = ma
then find the components...

3. The attempt at a solution

I know that I have to set up a free body diagram then break everything up into components. I also know that objects in equilibrium do not accelerate. But I can't figure out how to find the one mass. What equation would I use or what would I set things equal to?
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

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2. Sep 22, 2010

### Thaakisfox

Since the bodies are in equilibrium, they dont accelerate. Which means that the rope is keeping them still.
The tension in the rope is thus equal to the weight of m2. This is the equilibrium condition for m2.
Now try to right the condition up for m1. (i.e. the tension in the rope is equal to ...).

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