- #1
Iwanttolearn7
- 10
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Homework Statement
A 12000 kg car traveling at 10 m/s strikes and couples with a 6000 kg car at rest. What is the loss of mechanical energy in the collision?
Answer is 200,000 J.
Homework Equations
I want to know HOW to arrive at the correct answer above.
The Attempt at a Solution
Relevant equations tried:
1. Speed at final combination = Vf=(m1/m1+m2)Vi
=(12000/12000+6000)(10)
= 6.7 m/s
2. Kf-Ki
K= 1/2 mv^2
Kf= 1/2(12000)(6.7)^2 + 1/2(6000)(6.7)^2
= 269340 + 134670
= 404010
Ki= 1/2(12000)(10)^2 + 1/2 (6000)(10)^2
= 600,000 + 300,000
= 900,000
K=Kf-Ki
=404010 - 900,000
= -495990
=Not even close to the right answer.
I've done this problem over and over for two hours, not kidding, trying different combinations of equations, can someone please tell me where I am going wrong?
Thank you very much!
=
K