- #1
sunnnystrong
- 54
- 6
Homework Statement
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A 2.3 kg object traveling at 6.1 m/s collides head-on with a 3.5 kg object traveling in the opposite direction at 4.8 m/s. If the collisions is perfectly elastic, what is the final speed of the 2.3 kg object?
Homework Equations
Conservation of Energy:
1/2 m*vi^2 = 1/2 m*vf^2
Conservation of Momentum:
Pix = Pfx
The Attempt at a Solution
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Pix For 2.3 kg Object
(2.3kg)(6.1m/s) = (2.3kg)(Vf2) + (3.5kg)(Vf1)
Solving for Vf1 -->
[14.03 Ns - (2.3kg)(Vf2)]/3.5kg = Vf1
KE
1/2(2.3kg)(6.1m/s)^2 = 1/2(2.3kg)(Vf1)^2 + 1/2(3.8kg)(Vf2)^2
42.7915 = 1.15(Vf1)^2 + 1.9(Vf2)^2
Plugging in Vf1
42.7915 = 1.15(0.431837(Vf2)^2-5.26841Vf2 + 16.0686) + 1.9(Vf2)^2
Simplify and you get a quadratic:
0=2.39661 (Vf2)^2 - 6.05867 (Vf2) -24.3126
Solve for Vf2 = 4.69 m/s
Plug back into:
[14.03 Ns - (2.3kg)(Vf2)]/3.5kg = Vf1
Solve for Vf1 = 0.96m/s (which is definitely wrong)
I'm really confused & not sure how to solve for Vf1?