Two pendulums banging into each other problem.

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SUMMARY

The problem involves two pendulums, A and B, with pendulum A having a mass of 2.0 kg and pendulum B having an unknown mass. They collide at the midpoint of their arcs, with pendulum A coming to a complete stop and pendulum B moving backward at half its original speed. The conservation of momentum equation is applied, leading to a misunderstanding of the velocities involved. The correct approach requires recognizing that the velocities of the pendulums are not equal due to their opposite directions just before the collision.

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Homework Statement



A system contains two metal balls hanging from strings of length !.0 m. Pendulum A has a mass of 2.0 kg and B has a period of 2.0s. They are released from the same height at the same time and collide right in the middle of their arcs. If pendulum A comes to a complete stop while B moves backwords with half of its original speed, what is the mass of pendulum B?

Homework Equations



Conservation of momentum.


The Attempt at a Solution



My first thought was the conservation of momentum. 2Va+MbVb=-(1/2)MbVb. Of course there's 3 variables so i couldn't solve it but then i thought that since the balls were colliding in the middle of their arcs that maybe they're velocities were the same. So Va=Vb. From that logic I get that the mass of B is -4/3 which obviously makes no sense... I am not sure what I am doing wrong. I am gratful for any help. Thanks in advance
 
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tjhero123 said:

Homework Statement



A system contains two metal balls hanging from strings of length !.0 m. Pendulum A has a mass of 2.0 kg and B has a period of 2.0s. They are released from the same height at the same time and collide right in the middle of their arcs. If pendulum A comes to a complete stop while B moves backwords with half of its original speed, what is the mass of pendulum B?

Homework Equations



Conservation of momentum.


The Attempt at a Solution



My first thought was the conservation of momentum. 2Va+MbVb=-(1/2)MbVb. Of course there's 3 variables so i couldn't solve it but then i thought that since the balls were colliding in the middle of their arcs that maybe they're velocities were the same. So Va=Vb. From that logic I get that the mass of B is -4/3 which obviously makes no sense... I am not sure what I am doing wrong. I am gratful for any help. Thanks in advance


The momentum is a vector. The balls move in opposite directions just before they collide. Va is not equal to Vb.


ehild
 
Use the equation for the period of a pendulum to help you find Vb.
 
tannerbk said:
Use the equation for the period of a pendulum to help you find Vb.
The time taken is irrelevant. You cannot deduce any actual velocity since you do not know the original height. ehild's hint is the way forward.
 

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