PHYS 1023 Uark Exam 2 Study Guide
Questions and Answers with Complete
Solution | Latest Update 2026
Energy & Work
Energy – The ability of a system to perform work.
Work – Occurs when a force moves an object over a distance; both force and motion must be
present.
Gravitational Energy – Energy due to an object’s position in a gravitational field.
Kinetic Energy – Energy of motion.
Object’s Energy – The total work an object is capable of doing.
Elastic Energy – Energy stored in stretched or compressed objects.
Thermal Energy – Energy associated with heat.
System – A defined group of interacting objects and/or fields.
A system has energy if – It is capable of doing work.
Electromagnetic Energy – Energy carried by electric and magnetic fields.
Chemical Energy – Energy stored in chemical bonds and released during reactions.
Law of Energy (Conservation) – Energy cannot be created or destroyed, only transferred or
transformed.
Work-Energy Principle – Work is the transfer of energy.
Energy Efficiency – Useful output energy ÷ total input energy.
Power – Work done per unit time.
, 1 Watt – Equal to 1 joule per second.
Energy Transformations
Light bulb – Electrical → thermal + radiant energy
Falling book (just before impact) – Gravitational energy ≈ 0; energy is almost entirely kinetic
Hydroelectric plant – Gravitational energy (water) originates from solar (radiant) energy
Photosynthesis – Radiant → chemical energy
Burning match – Chemical → thermal + radiant energy
Drawing and releasing a bow – Chemical → elastic → kinetic energy
Thermodynamics
Second Law of Thermodynamics – Heat naturally flows from hotter to colder objects, not the
reverse.
Heat Engine – A device that converts thermal energy into work or other forms of energy.
Heat Engine Efficiency – Work output ÷ thermal energy input
Work Done (engine) – Input energy − exhaust energy
Maximum Efficiency – Heat engines can never reach 100% efficiency
Entropy – A measure of microscopic disorder
Entropy Rule – Total entropy cannot decrease; it can only increase or remain constant
Automobile Efficiency – Typically around 20%
Mixing substances – Increases entropy
Second Law Implication – Thermal energy cannot be completely converted into non-thermal
energy
Irreversible Process – Example: a block sliding to a stop (due to friction)
Questions and Answers with Complete
Solution | Latest Update 2026
Energy & Work
Energy – The ability of a system to perform work.
Work – Occurs when a force moves an object over a distance; both force and motion must be
present.
Gravitational Energy – Energy due to an object’s position in a gravitational field.
Kinetic Energy – Energy of motion.
Object’s Energy – The total work an object is capable of doing.
Elastic Energy – Energy stored in stretched or compressed objects.
Thermal Energy – Energy associated with heat.
System – A defined group of interacting objects and/or fields.
A system has energy if – It is capable of doing work.
Electromagnetic Energy – Energy carried by electric and magnetic fields.
Chemical Energy – Energy stored in chemical bonds and released during reactions.
Law of Energy (Conservation) – Energy cannot be created or destroyed, only transferred or
transformed.
Work-Energy Principle – Work is the transfer of energy.
Energy Efficiency – Useful output energy ÷ total input energy.
Power – Work done per unit time.
, 1 Watt – Equal to 1 joule per second.
Energy Transformations
Light bulb – Electrical → thermal + radiant energy
Falling book (just before impact) – Gravitational energy ≈ 0; energy is almost entirely kinetic
Hydroelectric plant – Gravitational energy (water) originates from solar (radiant) energy
Photosynthesis – Radiant → chemical energy
Burning match – Chemical → thermal + radiant energy
Drawing and releasing a bow – Chemical → elastic → kinetic energy
Thermodynamics
Second Law of Thermodynamics – Heat naturally flows from hotter to colder objects, not the
reverse.
Heat Engine – A device that converts thermal energy into work or other forms of energy.
Heat Engine Efficiency – Work output ÷ thermal energy input
Work Done (engine) – Input energy − exhaust energy
Maximum Efficiency – Heat engines can never reach 100% efficiency
Entropy – A measure of microscopic disorder
Entropy Rule – Total entropy cannot decrease; it can only increase or remain constant
Automobile Efficiency – Typically around 20%
Mixing substances – Increases entropy
Second Law Implication – Thermal energy cannot be completely converted into non-thermal
energy
Irreversible Process – Example: a block sliding to a stop (due to friction)
