Because then it could mess up the machine with to much energy
So the initial velocity is 15 m/s, the final velocity is 0 since it's at a complete stop and time is 10 seconds. Therefore:

Therefore, the acceleration is -1.5 m/s^2. The reason it's negative is due to the fact that the vector is going against it's original movement since it's decelerating.
Answer:
The Internal energy of the gas did not change
Explanation:
In this situation the Internal energy of the gas did not change and this is because according the the first law of thermodynamics
Δ U = Q - W ------ ( 1 )
Δ U = change in internal energy
Q = heat added
W = work done
since Q = W. the value of ΔU will be = zero i.e. No change