2 Energy, Work, and Heat Free Online FlashCards

How do kinetic and potential energy differ?

Kinetic energy is associated with motion; potential energy is associated with position or interactions, such as gravity or intermolecular interactions.

What energy components can make up a system’s total energy?

A system’s total energy can include internal energy and its overall kinetic and potential energies.

What is internal energy?

Internal energy, denoted by $U$, is the energy of microscopic motions and interactions among a system’s particles.

Why is internal energy called a state property?

Internal energy is a state property: its value depends on the system’s state, so $\Delta U$ is determined by the initial and final states.

What causes heat transfer, and which way does energy flow spontaneously?

Heat transfer is energy transfer caused by a temperature difference; energy flows spontaneously from higher to lower temperature.

What is work transfer in thermodynamics?

Work transfers energy through an organized interaction other than transfer driven solely by a temperature difference, such as a force moving a piston.

What determines whether energy transfer is heat or work?

The transfer mechanism determines whether energy crosses as heat or work, not what the energy becomes afterward.

Are heat and work stored properties of a system?

Heat and work describe energy crossing a system boundary; they are not forms of energy stored in the system.

What is the first law for a closed system under the stated sign convention?

For a closed system, $\Delta U = Q - W$, where $Q$ is heat transferred into the system and $W$ is work done by the system.

Under the stated convention, how does work done on a system affect its energy?

Work done on the system has the opposite sign to work done by it and tends to raise the system’s energy.

How do heat and work differ from the change in internal energy regarding the path?

Heat and work depend on the process taken between states, while the change in internal energy depends only on the endpoints.

What forms of microscopic kinetic energy do molecules have?

Molecules have microscopic kinetic energy from translation, rotation, and vibration.