Forces and Motion Study Guide

Vocabulary flashcards covering key concepts from the 8th grade Honors Science Forces & Motion study guide aligned to TEKS 8.6C and 8.7A–B.

Force

A push or pull on an object.

Net Force

The overall force after combining all forces acting on an object.

Inertia

An object's resistance to a change in its motion, which depends on and increases with mass.

Mass

The amount of matter in an object, which does not change with location.

Weight

The force of gravity on an object's mass, which can change with location.

Pressure

Force spread over an area, calculated as $\text{Pressure} = \frac{\text{Force}}{\text{Area}}$.

Equilibrium

A state where all forces are balanced and $\text{net force} = 0$.

Compression

A squeezing force pushing material inward.

Tension

A stretching/pulling force pulling material outward.

Friction

A force that resists motion between two surfaces in contact; opposes sliding.

Normal Force

The support force a surface pushes back with, perpendicular to the surface.

Gravity

A force that pulls objects toward each other (e.g., toward Earth's center).

Applied Force

A push or pull one object puts directly on another.

Newton's First Law

States that an object at rest stays at rest, and an object in motion stays in motion at a constant speed and direction, unless acted on by an unbalanced (net) force.

Newton's Second Law

States that acceleration depends on net force and mass, represented by $\text{Force} = \text{mass} \times \text{acceleration}$ ($F = m \times a$).

Newton's Third Law

States that for every action force, there is an equal and opposite reaction force acting on different objects at the same time.

Balanced Forces

Forces equal in size and opposite in direction that cancel out so $\text{net force} = 0$ and motion does not change.

Unbalanced Forces

Forces that do not cancel, creating a net force that causes an object to speed up, slow down, or change direction.

Speed

How fast an object moves without direction, calculated as $\text{Speed} = \frac{\text{distance}}{\text{time}}$.

Velocity

Speed with a direction (e.g., $5\,\text{m/s}$ north).

Acceleration

The change in velocity divided by time ($\text{Acceleration} = \frac{\text{change in velocity}}{\text{time}}$), which includes speeding up, slowing down, or changing direction.

Wind load

The sideways push of wind on a structure that engineers balance using structural frames or counterweights.