Work, Energy, and Power – Lecture Vocabulary

Key vocabulary terms covering foundational concepts, forces, and energy relationships discussed in Chapter 4: Work, Energy, and Power.

Work (W)

The product of force and displacement in the direction of the force; W = F·s, measured in joules (J).

Power (P)

The rate at which work is done or energy is transferred; P = W⁄t = F·v, measured in watts (W).

Kinetic Energy (KE)

Energy possessed by a moving object; KE = ½ m v².

Gravitational Potential Energy (GPE)

Energy stored due to height in a gravitational field; GPE = m g h.

Elastic Potential Energy (EPE)

Energy stored in a compressed or stretched spring; EPE = ½ k x².

Spring Constant (k)

Measure of spring stiffness; k = F⁄x, units N m⁻¹.

Coefficient of Kinetic Friction (μₖ)

The ratio of kinetic frictional force to the normal force, dimensionless.

Normal Force (N)

The support force exerted by a surface perpendicular to an object resting on it.

Inclined Plane Components

On a slope, weight splits into m g sin θ (parallel) and m g cos θ (perpendicular).

Conservation of Mechanical Energy

Without non-conservative forces, the sum of KE and PE remains constant.

Non-Conservative Force

A force (e.g., friction) that converts mechanical energy into other forms, causing energy loss.

Hooke’s Law

The restoring force of a spring is proportional to displacement; F = k x.

Joule (J)

SI unit of work or energy; one joule equals one newton-meter.

Watt (W)

SI unit of power; one watt equals one joule per second.

Ideal Smooth Pulley

A frictionless pulley that changes the direction of a force without altering the magnitude of work.