(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

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?

2. Relevant 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

3. 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.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Perfectly Inelastic collisions

**Physics Forums | Science Articles, Homework Help, Discussion**