Internal Energy (CIE A Level Physics)

For an ideal gas, internal energy is directly proportional to temperature in kelvin.

A sample of ideal gas is in a perfectly insulated box of fixed volume.

The temperature of the sample rises from 400 K to 600 K. Its internal energy was initially 2800 J.

Calculate its new internal energy.

Calculate the increase in total kinetic energy of the particles in the ideal gas.

The sample contains 3 moles of ideal gas.

Calculate the number of atoms in the sample.

Calculate the average kinetic energy of a particle in the sample of ideal gas after it has been heated.

Draw three lines on Fig 1.1 between the corresponding effects on internal energy and changes to the system.

Fig 1.1

The internal energy of an ideal gas increases. 

Describe the change in average particle motion.

Name two ways the internal energy of the system may be increased.

The volume of a container filled with an ideal gas is reduced. In this process, 3.5 kJ of work is done on the system.

At the same time, 1.2 kJ of thermal energy is transferred from the system to its surroundings. 

Calculate the change in internal energy.