Forces and Motion

Force

A push or a pull

balanced forces

Equal forces acting on an object in opposite directions

unbalanced forces

forces acting on an object that combine and form a net force that is not zero

Motion

An object's change in position relative to a reference point.

Friction

A force that opposes motion between two surfaces that are in contact

kinetic friction

Friction between moving surfaces

static friction

Friction that acts on objects that are not moving

sliding friction

friction that occurs when one solid surface slides over another

rolling friction

friction that occurs when an object rolls over a surface

fluid friction

friction that occurs as an object moves through a fluid

net force

The combination of all forces acting on an object

Newton's 1st Law of Motion

An object at rest stays at rest or an object in motion stays in motion

free body diagram

a diagram showing all the forces acting on an object

Applied Force

a force which is applied to an object by a person or another object

normal force

the force perpendicular to a surface that prevents an object from falling through the surface

Gravity

A force of attraction between objects that is due to their masses.

Contact forces

forces where the objects need to be physically touching to work

noncontact force

a force that one object can apply to another object without touching it

terminal velocity

the constant velocity of a falling object when the force of air resistance is equal in magnitude and opposite in direction to the force of gravity

magnitude

Greatness of size, strength, or importance

Inertia

The tendency of an object to resist a change in motion

Newton's 2nd Law of Motion

Force = mass x acceleration

Newton's 3rd Law of Motion

For every action there is an equal and opposite reaction

acceleration

The rate at which velocity changes

air resistance

Fluid friction acting on an object moving through the air