Momentum and law of conversation of momentum.

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SUMMARY

The discussion clarifies the definitions of momentum and the law of conservation of momentum. Momentum is defined as the product of mass and velocity, expressed mathematically as momentum = mass * velocity, where velocity is a vector quantity. The conservation of momentum states that the total momentum before a collision equals the total momentum after the collision. An example illustrates this principle using a 5 kg ball colliding with a 10 kg ball, demonstrating how to calculate the momentum of each object before and after the collision to ensure the total momentum remains constant.

PREREQUISITES
  • Understanding of basic physics concepts, specifically momentum and vector quantities.
  • Familiarity with non-relativistic formulas in physics.
  • Knowledge of collision types and their effects on momentum.
  • Ability to perform calculations involving mass and velocity.
NEXT STEPS
  • Study the principles of elastic and inelastic collisions in physics.
  • Learn about vector addition and its application in momentum calculations.
  • Explore advanced topics in momentum conservation, such as multi-body collisions.
  • Investigate real-world applications of momentum conservation in sports and engineering.
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Students of physics, educators teaching mechanics, and anyone interested in understanding the principles of momentum and its conservation during collisions.

winkle
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can anybody please explain these two definations?
i know momentum is the mass in motion..but how do we use the formula...explain please

thx
 
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basic non-relativistic formulas:
momentum = mass * velocity (note: velocity is not speed, velocity is a vector quantity)
and the conservation of momentum means:
momentum (before) = momentum (after)

For example:
a 5 kg ball is traveling at 1m/s : its momentum is 5*1 = 5 kg*m/s
if it hits a different ball (which is 10 kg) directly on and bounces directly back at 0.5 m/s. (directly on so that the other ball will head in the same direction as the inital ball was.
then the total momentum after the collision will still have to be 5 kg*m/s
we know that the first ball has momentum of -0.5 m/s * 5 kg = -2.5kg*m/s. Therefore the momentum of the second ball must be 7.5 kg*m/s so that the total momentum in the system is still 5 kg*m/s. From this the velocity of the second ball can be determined.
 
No, momentum is not "the mass in motion". You have to be a lot more precise than that: momentum is "mass times velocity". It is, as dmoravec said, a vector quantity; scalar mass times vector velocity.
To use that formula, calculate the total (vector) momentum of each particle before a collision, then after the collision and set them equal. The momentum of individual particles might have changed but the total is "conserved"- remains the same.
 

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