No, the kinetic energy of the molecule does not increase.

Explanation

As we know that kinetic energy of ideal gas is given by

……(i)

Where K. E=kinetic energy of gas

k_B = Boltzmann constant

T = temperature of gas

The Boltzmann constant is a physical constant that relates the average

kinetic energy of particles in a gas with the temperature of the gas.

Since k_B is a constant, kinetic energy of gas is proportional to

temperature of gas. Also, we know

…….. (ii)

Where v= velocity of gas

From equation (i) and equation (ii), we can say that the Kinetic energy of a gas is dependent on two factors-

1. Temperature (K.E. ∝ T)

2. Velocity (K.E. ∝ velocity²)

We can conclude that kinetic energy of gas will change only when there is a change in velocity of gas which in turn will change the temperature of gas. So, if van moves with uniform velocity (i.e. constant speed) no change in kinetic energy or temperature will be observed. Kinetic energy and temperature of the gas will only change when the van either decelerate or accelerate (rate of change of velocity).