- #1

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## Summary:

- elastic or inelastic collision?

If the initial kinetic energy is equal to the final kinetic energy where two objects that collide stick together, this collision is elastic or inelastic?

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- Thread starter Mohamad
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- #1

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- 1

## Summary:

- elastic or inelastic collision?

If the initial kinetic energy is equal to the final kinetic energy where two objects that collide stick together, this collision is elastic or inelastic?

- #2

BvU

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What collision scenario do you have in mind ?

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Clearly you do not understand the basic definitions of elastic and inelastic collision. You could at least look those up before proceeding.Summary:elastic or inelastic collision?

If the initial kinetic energy is equal to the final kinetic energy where two objects that collide stick together, this collision is elastic or inelastic?

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HallsofIvy

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I thought we weren't supposed to spoon-feed the answers.giventhat kinetic energy is conserved so this has to be an elastic collision.

I had already asked him to look up the defintions so that he could figure that out for himself.

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So your scenario is contradictory. Either the bodies don't stick together, or the kinetic energy isn't conserved, you cant have both. OR there are external forces in play.

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jbriggs444

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Or the objects were spinning just right so that they could latch onto one another without dissipating any energy. They can then spin about one another, each retaining its original (and rotational) kinetic energy in the combined center-of-momentum frame.So your scenario is contradictory. Either the bodies don't stick together, or the kinetic energy isn't conserved, you cant have both. OR there are external forces in play.

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The way I interpreted "stick together" is that they have exactly the same velocity after the collision. In the scenario you describe they don't have the same velocity after the collision (spinning about one another means they have opposite and equal velocities (in the best scenario) if I understand it properly)Or the objects were spinning just right so that they could latch onto one another without dissipating any energy. They can then spin about one another, each retaining its original (and rotational) kinetic energy in the combined center-of-momentum frame.

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jbriggs444

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Yes, the typical assumption with "stick together" is a head-on collision, ignoring the possibility of a resulting rotation. But a literal reading of the problem statement in #1 above allows the possibility.The way I interpreted "stick together" is that they have exactly the same velocity after the collision. In the scenario you describe they don't have the same velocity after the collision (spinning about one another means they have opposite and equal velocities (in the best scenario) if I understand it properly)

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