Check your understanding (Module 5.0)

Which of the following is NOT a part of the internal energy of an object?

• gravitational force of the Earth on the particles

• rotational kinetic energy of constituent particles

• translational kinetic energy of constituent particles

• potential energy associated with intermolecular forces

Which of the following statements is/are true for a contracting gas?

• work done on the gas by the surroundings is negative

• work done by the gas on the surroundings is negative

• work done by the gas on the surroundings is positive

• both A and B

Which of the following cases result/s to an increase in the internal energy of the system?

• surroundings doing negative work on the system

• surroundings doing positive work on the system

• system doing positive work on its surroundings

• both B and C

Consider the given figure. What can be correctly said about the work done by the popcorn on the lid?

• negative

• positive

• zero

• cannot be determined

A gas is inside a container fitted with a piston. The gas is heated, absorbing 50 kJ of heat. During this process, the gas expands, exerting 30 kJ of work on the piston. What is the change in the internal energy of the gas?

• -80 kJ

• -20 kJ

• 20 kJ

• 80 kJ

A thermodynamic system undergoes a process in which its internal energy decreases by 500 J. Over the same time interval, 220 J of work is done on the system. How much heat is transferred?

• 280 J released by the system

• 280 J absorbed by the system

• 720 J released by the system

• 720 J absorbed by the system

A system undergoes a process that can be split into two subprocesses: (1) a heating up subprocess with no work done, causing the system to absorb 40 kJ of heat, and (2) an expansion subprocess with no heat transfer. If the total change in internal energy of the system is 20 kJ, what is the work done by the gas in the expansion subprocess?

• 60 kJ

• 20 kJ

• -20 kJ

• -60 kJ

Which of the following systems has a decreasing internal energy?

• boiling water

• roof during a sunny afternoon

• marshmallow placed near a bonfire

• ice tray filled with water placed inside a freezer