Momentum Vs. Kinetic Energy: What's the difference?

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Homework Help Overview

The discussion revolves around understanding the differences between momentum and kinetic energy, particularly in the context of calculating the energy required to divert a speeding asteroid. Participants are exploring the appropriate application of these concepts in a practical scenario involving mass and velocity.

Discussion Character

  • Conceptual clarification, Problem interpretation, Assumption checking

Approaches and Questions Raised

  • Participants are attempting to determine whether to use momentum or kinetic energy for calculations related to diverting an asteroid. Questions about the definitions and applications of these concepts are raised, particularly in relation to energy expenditure for the task at hand.

Discussion Status

The discussion is active, with participants providing insights into the concepts of kinetic and potential energy, as well as momentum. Some participants suggest alternative strategies for addressing the problem, while others seek clarification on the correct approach to use in their calculations.

Contextual Notes

There are indications of uncertainty regarding the specific calculations needed, as well as the implications of using either momentum or kinetic energy in the context of diverting an asteroid. Participants are also considering the practical aspects of energy expenditure in this scenario.

winston2020
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Could someone please explain the difference between these two? I understand that they're obviously different, but I can't figure out where each of them should be used.

For example, I need to calculate how much energy it would take to stop a speeding asteroid. I have it's mass, and velocity, but I don't know whether I should calculate Momentum or Kinetic energy.
 
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winston2020 said:
For example, I need to calculate how much energy it would take to stop a speeding asteroid.
If you are going to spend your energy to stop an asteroid, you are on wrong way. Try to find a way to GET energy from the asteroid. :smile:
 
jdg812 said:
If you are going to spend your energy to stop an asteroid, you are on wrong way. Try to find a way to GET energy from the asteroid. :smile:

Well, that would be a good idea, but I'm essentially trying to find out how much energy it has... :-p
 
winston2020 said:
Well, that would be a good idea, but I'm essentially trying to find out how much energy it has... :-p
First of all, it has KINETIC energy.
If it is close to the Sun or the Earth, it has POTENTIAL energy as well...

P.S.
If you indeed would stop the asteroid near the Earth, you would spend rest of your life and your money TO KEEP IT IN REST! :smile:
 
jdg812 said:
First of all, it has KINETIC energy.
If it is close to the Sun or the Earth, it has POTENTIAL energy as well...

P.S.
If you indeed would stop the asteroid near the Earth, you would spend rest of your life and your money TO KEEP IT IN REST! :smile:

I understand that. I don't want to stop it. I'm going to use a series of blasts placed approximately 20 degrees to the back of the asteroid to divert it off course. But to calculate how far it will be diverted, I need to know how much energy it has in the forward direction. What I don't know, is if I should use E = 1/2mv^2 OR P=mv.
 
E = 1/2mv^2, this is energy, better use (mv^2)/2 to avoid misunderstanding

P=mv this is momentum
 
jdg812 said:
E = 1/2mv^2, this is energy, better use (mv^2)/2 to avoid misunderstanding

P=mv this is momentum

I know that too :p

What I need to know is in which sense they should be used. To figure out how much energy needs to be used to divert the asteroid, would I use momentum, or kinetic energy?
 
winston2020 said:
I understand that. I don't want to stop it. I'm going to use a series of blasts placed approximately 20 degrees to the back of the asteroid to divert it off course.

90 degrees would be better... less energy needed...

You may start with momentum of asteroid, then add 20% (or less, or more) in perpendicular direction... then calculate energy you spent...
 

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