Momentum & Pulleys Homework: Solving for Velocity

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SUMMARY

The discussion focuses on solving a physics problem involving momentum and pulleys, specifically addressing the calculation of velocity during a collision. The initial attempt incorrectly assumed conservation of momentum without accounting for velocity loss during the collision. The correct approach involves using impulse, defined as the product of force and the time of collision (F.dt), to calculate the change in momentum for all involved bodies. This method emphasizes the importance of considering the forces that cause momentum changes rather than applying general collision formulas blindly.

PREREQUISITES
  • Understanding of basic physics concepts, specifically momentum and impulse.
  • Familiarity with collision mechanics and conservation laws.
  • Knowledge of vector components in physics, particularly in vertical and horizontal directions.
  • Ability to apply mathematical equations related to force and momentum changes.
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  • Study the principles of impulse and momentum in detail.
  • Learn how to analyze collisions in one and two dimensions.
  • Explore the effects of external forces on momentum during collisions.
  • Practice solving problems involving pulleys and multiple bodies in motion.
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Students studying physics, particularly those focusing on mechanics, as well as educators and tutors looking for effective methods to teach collision dynamics and momentum conservation.

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Homework Statement


attachment.php?attachmentid=32922&stc=1&d=1299766402.jpg



The Attempt at a Solution



Taking the pulley and strings, pan, ball, block as system ... momentum is conserved

therefore in Y direction(vertical) ...

-mv = -2mV + mV
-mv = -mV
v = V

which is incorrect (as i expected as there has to be some loss of velocity of particle in a collision)

How should i do it?
 

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Try doing this using impulse:
Let the time of collision be dt and force be F.
Use F.dt = change in momentum for all the 3 bodies, then find the final velocity.
 
ashishsinghal said:
Try doing this using impulse:
Let the time of collision be dt and force be F.
Use F.dt = change in momentum for all the 3 bodies, then find the final velocity.

WARNING: This method by me is a general method of solving collision questions. This is not to be used blindly in this case. Consider the forces which brings the change in momentum.
 

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