Is this collision elastic, inelastic or totally inelastic? And why?

13) A 480-kg car moving at 14.4 m/s hits from behind a 570-kg car moving at 13.3 m/s in
the same direction. If the new speed of the heavier car is 14.0 m/s, what is the speed of the
lighter car after the collision, assuming that any unbalanced forces on the system are
negligibly small?
A) 13.6 m/s
B) 10.5 m/s
C) 19.9 m/s
D) 5.24 m/s
Answer: A

Question

Is this collision elastic, inelastic or totally inelastic? And why?

13) A 480-kg car moving at 14.4 m/s hits from behind a 570-kg car moving at 13.3 m/s in
the same direction. If the new speed of the heavier car is 14.0 m/s, what is the speed of the
lighter car after the collision, assuming that any unbalanced forces on the system are
negligibly small?
A) 13.6 m/s
B) 10.5 m/s
C) 19.9 m/s
D) 5.24 m/s
Answer: A

irishboy123 · Answer

its inelastic because there is a marginal difference in the answer , if you do it assuming it is elastic and thus kinetic energy is conserved (13.589 m/s), as opposed to doing it properly by conservation of momentum (13.57 m/s).  

in both cases however i think you would get this question right.

btw, the new speed of the heavier car would be 14.3 if this were truly elastic.

anonymous · Answer

But it's inelastic due to the bumpers of the car absorbing the energy, right?

irishboy123 · Answer

yes, stuff like that.

heat basically.  brakes? all  depends i suppose.