Answer:
a) the mass of the second car = 28000 kg
b) the amount of kinetic energy that was lost in the collision = 
Explanation:
Given that:
mass of the train car
= 6300 kg
speed of the train car
= 12.0 m/s
mass of the second moving car
= ???
speed of the second moving car
= 2.2 m/s
After strike;
they both move with a speed
= 4.00 m/s
a)
Using the conservation of momentum :







b)
To determine the amount of kinetic energy that was lost in the collision;
we will need to find the difference between the kinetic energy before the collision and after the collision;
i.e







Now; the kinetic energy that was lost in the collision is calculated as follows:




As the artic fox has very small ears it helps prevent the heat from his body from escaping quickly.
The bigger the ears the faster the heat escapes basically.
False I think
Hope this helped ^^;
It's a direct proportion. But the procedure you described is wrong and won't give you the correct answers.