Motion is a change in positionSpeed is change in position over timeVelocity is speed plus directionAcceleration is change is speed or velocity over time a =

(vf - vi)/t

+a is speeding up -a is slowing down

Newton’s 1st lawAn object that is in motion will remain in motion until acted

on by an outside force.What is Force?

A Push or a PullPush on your Science Book and it moves along the deskPush the same amount on a smaller book and it moves faster.

Newton’s 2nd lawA force acting on an object will cause that object to

accelerate in the direction of the force.F = m x aa = F / mm = F / a

Why don’t things keep going after you apply a force?

FrictionMicro welds formed between the microscopic bumps of the

surfaces.

Friction Static Friction

The friction between two surfaces that are not moving past each other.

Sliding FrictionThe force that opposes motion between two surfaces that are

sliding past each other.Rolling Friction

The frictional force between a rolling object and the surface it rolls on.

Air ResistanceFriction that occurs between an object and the

medium (air) that it is moving through.Like other forms of friction it acts in the

opposite direction to the motionAir resistance (amount) depends on the speed,

size and shape of the object rather than the mass.

Terminal Velocity – the velocity where the force of air resistance is equal to the force accelerating the object.

GravityThe Law of Gravitation

Anything that has mass is attracted to everything else that has mass.

Gravity is one of the four basic forces in the Universe.

Gravity – Attraction that varies with Mass and DistanceStrong Nuclear and Weak Nuclear – Attraction that acts

within the nucleusElectromagnetic – Electricity, Magnetism & Chemical

reactions

GravityThe range of the force of gravity is the

universe.Everything in the universe is attracted to

everything else.The planet Neptune was found because of the

affect of its gravity on the orbits of the other planets.

The force of gravity follows the same formulaF=m•a

Near the earths surface a = 9.8 m/s2

GravityGravitational force on an object is the weight.

Weight is measured in NewtonsAn object that masses 100 kg weighs 980 N

Free FallObjects that are falling at the rate of gravitational

acceleration will appear to float.Astronauts seem to float because both they and the

capsule they are in are falling toward the Earth at the same rate.

At 1000km from the Earth’s surface the force of gravity is only ¾ of what it is at the surface

GravityIn a gravity field all projectiles follow a curved

path.Centripetal Acceleration and Force

Acceleration or force towards the center of the curve.

Projectiles have both horizontal and vertical velocities at the same time.The Moon is constantly falling toward the Earth.The Earth is constantly falling toward the Sun.

Newton’s 3rd lawFor every action there is an equal and opposite reaction

Action and Reaction Forces act on different objectsA swimmer pushes on the water and the water pushes them

forward.Rocket Propulsion

Hot gas is thrown out the back at high speed and the rocket moves in the opposite direction.

Momentum A property of matter due to its mass and velocity

p = m x v

Changing momentum over time is ForceF = (mvf – mvi)/t

Law of Conservation of MomentumAfter a collision of a cue ball with the rack on a

pool table the total momentum of the pool balls equals the momentum of the cue ball at the moment it hit.