Speed can be defined as the ratio of the distance (d) traveled to the time (t) taken to cover that distance
Speed = distance/time -----(1)
In the given example since the distance is fixed an increase in the time of the trip will increase the denominator in equation(1) thereby decreasing the speed.
Adiabatic. This is a process where no heat is being added or removed from the system. Or can be simply stated as: no heat transfer (or heat flow) happening in a system.
