Question

When a truck carrying LPG cylinders moves with a uniform velocity on the road, the temperature of the gas molecules inside the cylinder 
1. increases
2. decreases
3. remains unchanged
4. none of the above

Answer 1

Correct Answer - Option 3 : remains unchanged

The correct answer is option 3) i.e. remains unchanged

CONCEPT:

• Kinetic theory of gas: The kinetic theory of gas assumes that the molecules of a gas are in constant random motion and frequently collide with each other and also collide on the walls of its container.
  • ​The kinetic energy of the gas comes from the temperature of the gas. Greater the temperature, the more the kinetic energy

The kinetic energy of molecules of an ideal gas is given by:

\(KE =\frac{3}{2}nRT\)

Where n is the number of moles of gas, R is the universal gas constant, and T is the absolute temperature of the gas.

EXPLANATION:

• LPG is liquefied petroleum gas commonly known as cooking gas.
• When the truck moves with uniform velocity, the centre of mass of the gas molecules also moves with uniform velocity.
• As a result, there will be no change in the relative motion of gas particles and trucks.
• Hence, the velocity of gas particles does not change i.e. kinetic energy does not change.
• The temperature of gas molecules is a measure of their kinetic energy.
• As kinetic energy does not change, the temperature will also not change.