C.
Thanks me later, that's my answer.
It would be the first one
You can use the impulse momentum theorem and just subtract the two momenta.
P1 - P2 = (16-1.2)(11.5e4)=1702000Ns
If you first worked out the force and integrated it over time the result is the same
<span>In an internal combustion engine, heat flow into a gas causes it to expand.
The application of direct force to specific parts of the engine will produce </span>expansion of the high-temperature<span> and high-</span>pressure<span> gases. Which will transform the chemical energy from the fuel (such as gasoline or oi) into mechanical energy.</span>