What is the speed of each marble immediately after the collision?

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Homework Help Overview

The problem involves two marbles, one moving and one at rest, and asks for their speeds immediately after a collision. The context is centered around the principles of elastic collisions in physics.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to apply a formula for a completely inelastic collision but questions the validity of their result. Some participants suggest reconsidering the type of collision and the relevant formulas for elastic collisions.

Discussion Status

Participants are exploring the distinction between elastic and inelastic collisions. There is a discussion about the conservation of kinetic energy and momentum, with some guidance provided on the principles involved in elastic collisions.

Contextual Notes

There is an assumption that the collision is elastic, which has not been explicitly stated in the original problem. The original poster's approach may be limited by this assumption.

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Homework Statement



A 43.0 marble moving at 1.90 strikes a 30.0 marble at rest. What is the speed of each marble immediately after the collision?

(vfx)1=?

(vfx)2=?

Homework Equations



v2f=2 m1 v1 / (m1 + m2)

The Attempt at a Solution



I tried using the equation above to get the first speed and is not the right answer. I did this 1.9m/s(2(.43)/.43+.30)=2.23m/s that apparently is wrong. Any help?
 
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Marbles usually collide elastically. You assumed completely inelastic collision, when the marbles stick together.

ehild
 
so what's the formula for that?
 
Think about what an elastic collision is... When all of the energy from on marble is transferred to another - where all kinetic energy is transferred to the next marble?

Where kinetic energy E = 1/2 mv^2

The initial energy of 1 and the initial energy of 2 must equal the final energy...
 
The energy is not transferred to one marble to the other, but conserved, just like the momentum.

The sum of the energies of both marbles is the same before and after collision.

ehuild
 

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