2 objects pulling on ice

  • Thread starter n4rush0
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  • #1
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Homework Statement


Man with mass M pulling with constant horizontal force F along a rope attached to object with mass m. Both the man and the object are on a frictionless surface and separated by distance D. When the man and object meet, what is the velocity of the object? Velocity of the man?


Homework Equations





The Attempt at a Solution


Fnet = ma
Assume motion inwards is positive.
T - F = Ma(subM)
T - F(subobject) = ma(object)

When I draw the free body diagram, what force does the object exert on the rope? How can I "classify" this force? There's no friction, so where would the force of the object come from?
 

Answers and Replies

  • #2
rl.bhat
Homework Helper
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Since there is no external force acting on the system, the center of mass remains at rest.
Let r1 be the distance of M from c.m., and r2 be the distance of m from c.m. such that
Mr1 = mr2. And r1 + r2 = D.
Both man and mass experience equal and opposite force F.
The acceleration of man is a1 = F/M, and acceleration of mass is a2 = F/m. They meet at c.m.
Man and mass start from rest. So vi = 0.
Now using kinematic equation find v1 and v2.
 
  • #3
14
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Thanks, I wasn't sure if I could say the force on the man and force on the object both equal F.
 

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