iGCSE Physics (0625) 2.2.2 Specific heat capacity-Exam Style Questions- New Syllabus
▶️ Answer/Explanation
Detailed solution:
Temperature is a macroscopic measure of the average kinetic energy of the particles in a substance.
When a gas cools, its temperature $\theta$ decreases, which directly corresponds to a reduction in the average kinetic energy $E_{k}$ of its constituent molecules.
The internal energy of an ideal gas is primarily determined by the sum of the kinetic energies of all its particles.
Therefore, a decrease in internal energy during cooling is caused by the particles moving more slowly on average.
Option C and D describe changes that would typically increase energy or occur during expansion, while B is irrelevant to thermal cooling.
Thus, the decrease in internal energy is due to a decrease in the average kinetic energy of the gas particles.
Question
The diagram shows a frictionless piston inside a cylinder. The air inside the cylinder is heated. The piston moves in the direction shown
Which statement about the air inside the cylinder is correct?
A The temperature and volume increase at constant pressure.
B The temperature and pressure increase at constant volume.
C The temperature, volume and pressure all increase.
D The volume and pressure increase at constant temperature.
▶️Answer/Explanation
Ans A
Question
Solids expand when heated and contract when cooled. In which example is there a useful application of expansion and not an unwanted effect?
A bridges
B railway lines
C telephone cables
D thermostats
▶️Answer/Explanation
Ans D