- #1

chamonix

- 21

- 0

## Homework Statement

In 1986, four high school students built an electric car that could reach a speed of 106 km/h. The mass of the car was just 60.0 kg. Imagine two of these cars performing in a stunt show. One car travels east with a speed of 106.0 km/h and the other travels west with a speed of 75.0 km/h. If each car is driven by a person with mass of 50.0 kg, how much kinetic energy is dissipated in a head on, perfectly inelastic collision?

## Homework Equations

I used these three equations:

m1*v1i+m2*v2i=(m1+m2)vf

KEi=1/2*m1*v1i^2+1/2*m2*v2i^2

KEf=1/2*(m1+m2)vf^2

KE=KEi-KEf

## The Attempt at a Solution

I've tried many attempts, but I think this one is most relevant...

m1*v1i+m2*v2i=(m1+m2)vf

(110kg)*(29.4m/s)+(110kg)*(-20.8m/s)=(220kg)vf

vf=4.3m/s

KEi=1/2*m1*v1i^2+1/2*m2*v2i^2

KEi=1/2*110kg*29.4m/s^2+1/2*110kg*-20.8^2

KEi=71335J

KEf=1/2*(m1+m2)vf^2

KEf=1/2*(220)4.3^2

KEf=2033.9J

KE=KEi-KEf

KE=71335-2033.9

KE=69301.1J

KE=69300 Joules

I think that I used all the right equations, but the answer is wrong. Any help is most appreciated. Thanks.