Physics 0625 · IGCSE · Kinetic particle model of matter

Kinetic particle model of matter — practice question

A fixed amount of gas is confined by a piston inside a cylinder with thin metal walls. The piston can slide freely in the cylinder with no friction. Fig. 4.1 shows the cylinder and piston. The diagram labels gas, cylinder and piston. The cylinder is placed inside a freezer.
(a(i))[2]

Calculate the force exerted on the piston by the air in the freezer.

(a(ii))[2]

As soon as the cylinder is put into the freezer, the gas temperature inside the cylinder falls and the air forces the piston further into the cylinder. Calculate the work done on the piston by the air in the freezer as the air pushes the piston a distance of 0.021 m into the cylinder.

(b)[2]

Calculate the change in the internal energy of the cylinder.

(c)[3]

When the temperature reaches $-18^\circ$C, the gas pressure in the cylinder is still the same as the atmospheric pressure. Explain, in terms of the particles of the gas, why the pressure stays equal to its original value.

(d)[2]

As the temperature of the metal cylinder falls, its volume also falls. The reduction in the metal's volume is much smaller than the reduction in the gas volume. Explain, in terms of the particles of the metal, why the decrease in the metal's volume is smaller than that of the gas.

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