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Gravity Pulling Blocks

  • Thread starter anastasiaw
  • Start date
  • #26
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So for the block m1, m1a=T-m1gsin25-/mu*m1gcos25. And that is solving for? The net force right?

Forces acting on m2 would be gravity pulling down, tension pulling up. And that's it right?
 
  • #27
rock.freak667
Homework Helper
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So for the block m1, m1a=T-m1gsin25-/mu*m1gcos25. And that is solving for? The net force right?

Yes but you don't know the value of T just yet.

Forces acting on m2 would be gravity pulling down, tension pulling up. And that's it right?
Yes that is right, so m2a= ?, now when you get this equation, you can find T and then out that into the first equation to get m1
 
  • #28
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so m2a=m2g-T
Then go through and do the math and T= 47.32.
Then I plug that in for T in the m1a=T-m1g*sin25-/mu*m1g*cos25

But how would I go about isolating m1?
 
  • #29
rock.freak667
Homework Helper
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so m2a=m2g-T
Then go through and do the math and T= 47.32.
Then I plug that in for T in the m1a=T-m1g*sin25-/mu*m1g*cos25

But how would I go about isolating m1?
Well you would just need to calculate the constants and then rearrange. a=3.05, you can calculate gsin25° and μgcos25°

So you'd have something like


Am1=47.32-Bm1-Cm1

Where A,B and C are constants.
 
  • #30
346
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You get all the terms with m1 in them to one side of the equation and factor the m1 out.
 
  • #31
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...If I divide out the m1 in order to get it to one side, won't that cancel out all the m1's?
 
  • #32
346
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You can't divide out because there is no m1 term in front of the T. That is why you have to get all the m1 terms on the same side and pull the common term (i.e. m1).
 
  • #33
rock.freak667
Homework Helper
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...If I divide out the m1 in order to get it to one side, won't that cancel out all the m1's?
No, the value of 'T' has no m1 in it. Just gather the like terms on side and then divide.
 
  • #34
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When I go through and divide everything out, I get 6.99kg... That doesn't seem possible?

And isn't the correct answer...
 
  • #35
13
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I went through and re-worked it. Got 4.472kg which is the correct answer. Thank you sooooo much Rockfreak. You have been an invaluable resource on this matter.
 

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