Two Blocks attached by a string, on an incline

  • Thread starter stripedcat
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  • #1

Homework Statement


In the diagram mA is equal to 3.00 kg and mB is equal to 1.07 kg. The angle of the inclined plane is 38.0°

6sq6bn.png


(a) Find Acceleration: 6.03 m/s^2 (got this part)
(b) Find the tension Tb in the connecting string: Not sure

Homework Equations



(a) a = (F/mA + mB)
(b) t = mA * a? or mB * a? Not sure

The Attempt at a Solution



Obviously my mA * a and mB * a both didn't work, I'm not sure what the formula should be.
 

Answers and Replies

  • #2
Doc Al
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What forces act on each block? Draw yourself a free body diagram for one of the masses. Then by applying Newton's 2nd law, you can solve for the tension.
 
  • #3
I'm sorry, but... What?

The force that acts on each block is gravity, 9.8 * sin theta. That's how I got acceleration.

T = m(g+a)? But is that mA or mB?
 
  • #4
Doc Al
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I'm sorry, but... What?

The force that acts on each block is gravity, 9.8 * sin theta. That's how I got acceleration.
Right, but you left it out in your two formulas for tension.

T = m(g+a)? But is that mA or mB?
Do this. Pick a block. Doesn't matter which. Then find ∑F for that block. Direction matters: call down the incline positive.
 
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  • #5
Right, but you left it out in your two formulas for tension.
Woops, sorry. O_O I missed that.

Do this. Pick a block. Doesn't matter which. Then find ∑F for that block. Direction matters: call down the incline positive.
3 * (9.8 + 6.03) = 47.49

I don't know what the summation F means. Sum of forces on the block?

I usually have practice problems so I can play with them until I figure out how to do them, no such luck on this one.
 
  • #6
Doc Al
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I don't know what the summation F means. Sum of forces on the block?
Yes.

Did you pick a block? Which one? What forces act on it? What's their sum?
 

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