Chapter 6: Work and Energy Flashcards

Vocabulary flashcards covering key definitions, formulas, and principles from Chapter 6: Work and Energy.

Work Done by a Constant Force

The work done on an object by a constant force $F$ is equal to the product of the force magnitude, the displacement magnitude $s$, and the cosine of the angle $\theta$ between them: $W = (F \cdot \cos(\theta)) \cdot s$.

Joule

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

Kinetic Energy

The energy possessed by an object of mass $m$ due to its motion at speed $v$, calculated as $KE = \frac{1}{2} m v^2$.

Work-Energy Theorem

The theorem stating that when a net external force does work $W$ on an object, its kinetic energy changes by an amount equal to that work: $W = \Delta KE = KE_f - KE_0$.

Gravitational Potential Energy

The energy an object of mass $m$ has by virtue of its position relative to Earth's surface, given by $PE = m g h$, where $h$ is height relative to an arbitrary zero level.

Gravitational Acceleration

The acceleration experienced by objects due to Earth's gravity, denoted by $g = 9.8\,\text{m/s}^2$.

Conservative Force

A force for which the work done in moving an object between two points is independent of the path taken and zero along any closed path, such as gravity or electrostatic forces.

Non-Conservative Force

A force for which the work done depends on the path taken, such as friction or air resistance.

Total Mechanical Energy

The sum of the kinetic energy $KE$ and potential energy $PE$ of an object, represented as $E = KE + PE$.

Principle of Conservation of Mechanical Energy

The principle stating that the total mechanical energy $E = KE + PE$ of an object remains constant ($E_f = E_0$) provided that the net work done by external non-conservative forces is zero ($W_{nc} = 0$).

Average Power

The average rate at which work $W$ is performed over a time interval $t$, calculated as $\bar{P} = \frac{W}{t} = F \cdot \bar{v}$, where $\bar{v}$ is average speed.

Watt

The SI unit of power, equal to one Joule of work performed per second ($1\,\text{W} = 1\,\text{J/s}$).

Principle of Conservation of Energy

The fundamental physical principle stating that energy cannot be created or destroyed, but can only be converted from one form to another.