Chapter 9 - Forces

Force

A push, pull or twist upon an object that results from its interaction with another object, changing its motion, speed, direction, or shape

Contact Force

A push, pull, or twist occurring by two objects physically touch each other

Non-contact Force

A push, pull, or twist occurring without two objects physically touch each other

Resultant Force/Net Force

Sum of all forces acting on an object

Newton’s First Law

Every body perseveres in its state of rest, or of uniform motion in a right line, unless it is compelled to change that state by forces impress'd thereon.

Newton’s Second Law

The alteration of motion is ever proportional to the motive force impress'd; and is made in the direction of the right line in which that force is impress'd.

Newton’s Third Law

To every Action there is always opposed an equal Reaction: or the mutual actions of two bodies upon each other are always equal, and directed to contrary parts.

Inertia

The natural tendency of an object to resist any change in its motion

Weight

The downward force created when gravity pulls on an object's mass

Mass

The measure of the amount of matter inside an object and how much inertia the object has

Volume

The amount of physical three-dimensional space an object takes up

Gravity

An invisible, mutual attractive force acting between any two objects that have mass

Normal Force

The supportive contact force exerted by a surface on an object in response to gravity and perpendicular to the surface