- #1

toesockshoe

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## Homework Statement

A 3 kg body (mass1) moving at 4 m/s makes an elastic collision with a stationary body(mass2) of mass 2 kg. Find the velocity of each body after the collision

## Homework Equations

pi=pf

w=delta e

## The Attempt at a Solution

so because it is elastic collision, it means that kinetic energy is conserved... we can do the following:

[itex] W=\Delta E [/itex]

[itex] 0= \Delta KE_1 + \Delta KE_2 [/itex]

[itex] 0= \frac{1}{2}m_1v_{f1}^2-\frac{1}{2}m_1v_{i1}^2+\frac{1}{2}m_2v_{2f}^2-\frac{1}{2}m_2v_{2i}^2 [/itex]

[itex] v_{f1} = \sqrt{\frac{m_1v_{i1}^2-m_2v_{2f}^2}{m_1}} [/itex]

ugh latex won't work:

vf1=((m1(v1f)^2-m2(v2f)^2)/m1)^1/2

now we can use momentum conservation to say

pi=pf

[itex]m_1v_{i1}=-m_1v_{f1}+m_2v_{f2} [/itex]

we know vf1 from the energy part so we have the following:

m_1v_{i1}=m_1\sqrt{\frac{m_1v_{i1}^2-m_2v_{f2}^2}{m_1}+m_2v_{f2} [/itex]

so i have one unknown ([itex] v_{f2} [/itex]) and one equation, but that seems awfully horrible to eliminate the final velcity of mass 2. am i even doing it correctly?

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