Work, Energy, Temperature, and Heat

Vocabulary practice flashcards covering fundamental concepts, definitions, formulas, and diagrams for introductory physics topics on Work, Energy, Temperature, Heat, and Thermodynamics.

Work ($W$)

Mechanically defined as the product of a constant force $F$ and displacement $d$ in the direction of the force ($W = Fd$), measured in joules ($\text{J}$).

Joule ($\text{J}$)

The SI unit of work and energy, defined as one newton-meter ($1\text{ N} \times \text{m}$).

Kinetic Energy ($E_k$)

The energy an object possesses because of its motion, given by the formula $E_k = \frac{1}{2}mv^2$.

Gravitational Potential Energy ($E_p$)

The energy an object possesses because of its height or position relative to a surface, given by the formula $E_p = mgh$.

Conservation of Energy

The fundamental principle stating that energy cannot be created or destroyed, only transformed from one form to another, remaining constant in total amount.

Simple Machine

Any elementary mechanism of which all complex machines are composed, including the lever, wedge, pulley, and screw.

Power ($P$)

The rate at which work is performed, defined as work done per unit time ($P = \frac{W}{t}$).

Watt ($\text{W}$)

The SI unit of power, equivalent to one joule per second ($1\text{ J/s}$).

Temperature

A measure of how hot or cold something is, corresponding to the average kinetic energy of the molecules in a substance.

Thermal Expansion

The increase in volume or dimensions of a substance when heated, accompanied by contraction when cooled.

Absolute Zero

The lowest possible theoretical temperature where all molecular motion ceases, designated as $0\text{ K}$ on the Kelvin scale.

Heat ($H$)

A form of energy transferred between objects as a result of a temperature difference.

Calorie ( ext{cal})

The amount of heat required to raise the temperature of $1\text{ g}$ of water by $1^\text{o}\text{C}$, equivalent to $4.2\text{ J}$.

Food Calorie

The unit of energy produced by nutrition, equivalent to $1000\text{ calories}$ or $1\text{ kilocalorie}$ ($1\text{ kcal}$).

Specific Heat ($c$)

The amount of heat required per unit mass to change the temperature of a substance by one degree, used in the heat formula H = mc\text{\textDelta}T.

Latent Heat

The heat absorbed or released by a substance during a phase change occurring at a constant temperature.

Latent Heat of Fusion ($L_f$)

The heat required to change $1\text{ kg}$ of a solid into a liquid at constant temperature ($80\text{ kcal/kg}$ for water).

Latent Heat of Vaporization ($L_v$)

The heat required to change $1\text{ kg}$ of a liquid into a gas at constant temperature ($540\text{ kcal/kg}$ for water).

Sublimation

The direct phase transformation of a substance from solid to gas without passing through the liquid phase.

Conduction

The transfer of heat by molecular collisions within a stationary material without mass movement.

Convection

The transfer of heat through the actual bulk movement of a fluid or material from one location to another.

Radiation

The transfer of heat via electromagnetic waves, which can propagate through empty space.

Methods of Heat Transfer

The three modes through which thermal energy moves from warmer to cooler objects: conduction, convection, and radiation.

Kinetic Theory of Gases

A physical model describing gases as composed of small particles moving independently in random directions at high speeds, where higher temperature corresponds to higher average particle speed.

Pressure ($P$)

The force exerted per unit area ($P = \frac{F}{A}$), measured in pascals.

First Law of Thermodynamics

The application of conservation of energy to thermodynamic systems: heat added equals the change in internal energy plus work done (H = \text{\textDelta}E_i + W).

Second Law of Thermodynamics

The principle stating that heat does not flow spontaneously from a colder body to a hotter body.

Heat Pump

A mechanical system that uses work input to force heat to flow from a low-temperature reservoir to a high-temperature reservoir.

Phase Change Heating Curve

A plot depicting temperature changes and constant-temperature phase transitions (A to B, C to D) as heat is continuously added to a substance.