# Another Physics Question

• Nov 7th 2012, 12:26 PM
Louisana1
Another Physics Question
A green 4 kg toy car with a speed of 5 m/s collides head-on with a stationary yellow 1-kg car. After the collision, the cars are locked together with a speed of 4 m/s. How much kinetic energy is lost in the collision?

a. What is the kinetic energy of the green 4-kg toy car BEFORE the collision?
b. What is the kinetic energy of the yellow 1-kg toy car BEFORE the collision?
c. What is the kinetic energy of the two cars AFTER the collision?
• Nov 7th 2012, 12:28 PM
skeeter
Re: Another Physics Question
$KE = \frac{1}{2}mv^2$
• Nov 7th 2012, 01:27 PM
Louisana1
Re: Another Physics Question
1/2(4)(5)^2=50J
1/2(1)(0)^2=0J
1/2(5)(4)^2=40J

Lost in collision 50-40=10 J

Is this correct
• Nov 8th 2012, 05:37 AM
topsquark
Re: Another Physics Question
Quote:

Originally Posted by Louisana1
1/2(4)(5)^2=50J
1/2(1)(0)^2=0J
1/2(5)(4)^2=40J

Lost in collision 50-40=10 J

Is this correct

Well I'm excited. You even included the units! (Most don't.)