Work, Energy, & Power

Work

The movement of an object by an external force over a distance, resulting in a transfer of energy.

Joule (J)

The standard unit of energy, named in honor of James Prescott Joule.

Work formula

$W = F \, d$, where $W$ is work done, $F$ is the force exerted, and $d$ is the distance moved.

Work with angle

For forces exerted at an angle, $W = F \, d \cos(\Theta)$, where $\Theta$ is the angle to the direction of motion.

Energy

The capacity to do work, representing the ability of an object to produce a change.

Potential Energy

Stored energy, such as a marble at the top of an incline.

Kinetic Energy

The energy of motion, such as a marble rolling down an incline.

Thermal Energy

The internal energy of movement of atoms causing an increase in temperature.

Work-Energy Theorem

The change in kinetic energy when work is done on an object, defined as $W = \Delta KE$.

Power

The rate at which work is done, defined as $P = \frac{W}{\text{time}}$.

Watt

The base unit of power, defined as one joule per second.

Conservation of Energy

The principle that energy cannot be created or destroyed, only changed from one form to another.

Mechanical Energy

The sum of kinetic and potential energy in a system.

Elastic Collision

A collision where kinetic energy is conserved and objects rebound without generation of heat.

Inelastic Collision

A collision where kinetic energy decreases, often resulting in heat or deformation.

Momentum

The product of an object's mass and velocity, represented as $p = m \, v$.

Conservation of Momentum

The total momentum of a closed system remains constant if no external forces act on it.

Angular Momentum

The product of rotational inertia and rotational velocity, represented as $L = I \, w$.

Work Done

The transfer of energy through a force applied over a distance.

Stopping Distance

The distance required for an object to come to a complete stop when applying a braking force.

Frictional Force

The force that opposes the motion of an object and reduces its kinetic energy.

Net Work

The total work done on an object, which results in a change in its kinetic energy.

Initial Velocity (v1)

The speed of an object before a specific event, such as a collision or force application.

Final Velocity (v2)

The speed of an object after a specific event, such as a collision or force application.

Average Velocity

The total displacement divided by the total time taken for that displacement.