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Newtons Third Law Problem

  • Thread starter SherBear
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  • #1
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Figure shows a block of mass resting on a slope. The block has coefficients of friction and with the surface. It is connected via a massless string over a massless, frictionless pulley to a hanging block of mass 2.0 kg.
i got this first one: What is the minimum mass that will stick and not slip?

1.83 kg
Correct

But can't get the second part:
If this minimum mass is nudged ever so slightly, it will start being pulled up the incline. What acceleration will it have?

knight_Figure_08_36.jpg


Thank you! :)
 

Answers and Replies

  • #2
ehild
Homework Helper
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1,876
Figure shows a block of mass resting on a slope. The block has coefficients of friction and with the surface.

Correct the sentence in red please. What are the coefficients of friction?

ehild
 
  • #3
PeterO
Homework Helper
2,425
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Figure shows a block of mass resting on a slope. The block has coefficients of friction and with the surface. It is connected via a massless string over a massless, frictionless pulley to a hanging block of mass 2.0 kg.
i got this first one: What is the minimum mass that will stick and not slip?

1.83 kg
Correct

But can't get the second part:
If this minimum mass is nudged ever so slightly, it will start being pulled up the incline. What acceleration will it have?

knight_Figure_08_36.jpg


Thank you! :)
Once the block starts moving, the coefficient of friction is then the kinetic coefficient, which will mean a smaller friction. Thus there is a net force up the slope [and down on the hanging mass] which causes the system to accelerate.
 
  • #4
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I'm really sorry about that ehild! The mu(s) is .8 but the mu(k) which I assume we use on this problem because it's moving therefore kinetic is .5 =-)
 
  • #5
81
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Once the block starts moving, the coefficient of friction is then the kinetic coefficient, which will mean a smaller friction. Thus there is a net force up the slope [and down on the hanging mass] which causes the system to accelerate.
Thank you Peter!
 
  • #6
ehild
Homework Helper
15,494
1,876
I'm really sorry about that ehild! The mu(s) is .8 but the mu(k) which I assume we use on this problem because it's moving therefore kinetic is .5 =-)
Everything is clear then. Can you solve the second part or still need help?

ehild
 
  • #7
81
0
Everything is clear then. Can you solve the second part or still need help?

ehild
Yes, it's clear. Thank you ehild! :)
 

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