The amount of matter present 

Applies to Gases, Liquids, & Solids

**Mass is NOT the same as weight

any property that can be characterized by ONE number.

(EX: Time, Mass, Distance)

Any property that can be characterized by two numbers

(EX: Speed is measured in mph)

Has both magnitude & direction

Other exampled of Vectors:

Veloctiy, Acceleration, Displacement

Newton's First Law

(Law of Inertia)

All bodies remain at rest or in a state of uniform motion UNLESS another force acts in opposition. 

In other words...

The tendency of a body in motion to remain in motion

&

the tendency of a body at rest to stay at rest

Mass per unit volume

Ex: 4 air molecules (LESS DENSE)

4 million air molecules (MORE DENSE)

*Density changes how air molecules travel*

Refers to the attractive gravitational force exerted on a mass by the earth

Weight of an object is DIRECTLY proportional to its mass.

Weight is a FORCE, not a quantity of matter present.

The property that enables recovery from distortion to either shape or volume

More properly defined as:

"The ability to resist changed in shape or volume rather than the ability to recover from such changes" 

The main property adressed in Newton's First Law

Inertia is DIRECTLY proportional to mass 

Think of mass as a measurement of Inertia-

Compare a Steel ball with Ping Pong Ball

(A massive object like the steel ball, a large force is needed to set the ball into motion, stop its motion, or to change its direction. Unlike the steel ball, the ping pong ball has neglibible mass, therefore small inertia because little force is needed to set the ping pong ball into motion, stop motion, or change direction)

Movement from an original position caused by an application of force. 

*The amplitude of displacement is PROPORTIONAL to the magnitude of force applied*

(In other words, the harder we strike the fork, the greater the amplitude of displacement from equilibrium)

FORCE= MASS x ACCELERATION

(Acceleration being a VECTOR)

(Mass being SCALAR)

Equilibrium: NO MOVEMENT 

Net Force=0

Meaning NO forces are acting upon the specified object

Displacement: Movement from equilibrium caused by an acting force

If a force is applied and motion occurs, the motion is opposed by FRICTION.

Friction occurs when two surfaces are in contact whith each other. 

With every force there must be associated an EQUAL reaction force of OPPOSITE direction.

A Force CAN NOT exist alone

(This is why we can not play tug of war by oneself) 

Exerting a force on the desk with your hand. 

The shape of your hand has been distorted because of the equal but opposite reacting force from the desk.

The reaction force exerted on your hand because the desk is elastic.

**ALL solid materials posess some degree of elasticity, therefore are able to exert forces.

Another term for vibration 

Two types of movement:

1) Transverse Wave

2) Longitudinal Wave

Direction of the vibration is at a RIGHT angle to the direction of the force that propogated the vibration.

EX: Pebble dropped in water.

(The force of the pebble is downward due to gravitational pull, causing the horizontal propagations of vibrations.)

Direction of the oscilation (vibration) is PARALLEL to the force that propagated the motion.

EX: Spring on top of a screen door