# Homework Help: Two cars collide, find temperature change

1. Feb 24, 2009

### Flip18064

1. The problem statement, all variables and given/known data

Two cars collide head on while each is traveling at 80 km/hr. Suppose all their kinetic energy is transformed into the thermal energy of the wrecks. What is the temperature increase of each car? (Assume each car's specific heat is that of iron)

2. Relevant equations

K = .5mv^2
Q = cm(delta T)
iron specific heat = .449 J/(g*K)

3. The attempt at a solution

K = 2(.5m(22.2)^2) = 492.8m

(converted 80 km/hr to m/s)

Q = 492.8m = (.449)(2m)T
T = 548.8 K
= 275.6 C

2. Feb 24, 2009

### minger

Well, for one, there is no reason to convert your units. You calculated a $$\Delta T$$, not a temperature, and $$\Delta °C = \Delta K$$. Is the correct answer 549.9 K?

3. Feb 24, 2009

### Flip18064

Oh yeah, I see what your saying. However 549 is still the wrong answer, so i must be doing something else wrong too.

4. Feb 24, 2009

### Flip18064

Can anyone help me? I am really stuck...