Transforming kinetic energy into thermal energy

  • Thread starter nlingraham
  • Start date
  • #1
16
0

Homework Statement



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

Homework Equations



K=1/2mv2

Q=mcΔT

1/2mv2=mcΔT

∴ ΔT=v2/2c


The Attempt at a Solution



I worked it out using 80 km/h for v and 449 J/kg * K for c and got 7.13 K. My question is if this is right, and if it is can someone explain to me how the units cancel out to give just K?
 

Answers and Replies

  • #2
6,054
391
Express J in terms of kg, m and s. What is the dimension of c then?
 
  • #3
16
0
Ok, I got it. J=kg*m2/s2. So that meant I had to convert 80 km/h to 22.22 m/s for everything to cancel out. I ended up getting .55 C. Thank you for your help.
 

Related Threads on Transforming kinetic energy into thermal energy

  • Last Post
Replies
6
Views
12K
  • Last Post
Replies
5
Views
858
  • Last Post
Replies
9
Views
955
Replies
1
Views
2K
  • Last Post
Replies
6
Views
23K
  • Last Post
Replies
2
Views
6K
  • Last Post
Replies
1
Views
15K
Replies
6
Views
29K
  • Last Post
Replies
0
Views
385
M
Replies
4
Views
5K
Top