Force & MotionForce & Motion

Newton’s Laws of MotionNewton’s Laws of Motion

MotionMotion

MotionMotion An object is in motion An object is in motion

if the object changes if the object changes position relative to a position relative to a reference point.reference point.

Speed with a direction is VelocitySpeed with a direction is Velocity

SpeedSpeed The speed of an The speed of an

object is the distance object is the distance it travels divided by it travels divided by the time it takes to the time it takes to travel the distance.travel the distance.

Speed = Distance/ TimeSpeed = Distance/ Time

VelocityVelocity The speed of an The speed of an

object moving in a object moving in a particular direction is particular direction is called its velocity.called its velocity.

AccelerationAcceleration

Acceleration Acceleration The rate at which the The rate at which the

velocity of an object velocity of an object changes is called changes is called acceleration.acceleration.

Force is a push or pull exerted on an Force is a push or pull exerted on an object. When you exert a force on an object. When you exert a force on an object, you can change the object’s object, you can change the object’s

motion.motion. Unbalanced Forces Unbalanced Forces

Cause an object to Cause an object to speed up, slow down, speed up, slow down, start/stop moving, or start/stop moving, or change direction.change direction.

Balanced ForcesBalanced Forces Balanced forces do Balanced forces do

not change an not change an object’s direction.object’s direction.

Work = Force X DistanceWork = Force X Distance

When you exert a When you exert a force on an object force on an object that causes the that causes the object to move, object to move, you have done you have done workwork

Introduction to Introduction to Forces and MotionForces and Motion

Forces at work at an Forces at work at an Amusement ParkAmusement Park

•Potential Energy Potential Energy

Stored energy Stored energy It can be released later to do workIt can be released later to do work Two typesTwo types

Gravitational – energy due to Gravitational – energy due to positionposition Example: yo-yo in your handExample: yo-yo in your hand

Elastic – energy due to compression Elastic – energy due to compression or stretching.or stretching. Example: wound up toyExample: wound up toy

• Kinetic EnergyKinetic Energy

Energy of moving objectsEnergy of moving objects Examples: moving bike, running Examples: moving bike, running

waterwater

Newton’s First Law:Newton’s First Law:Also Known as “The Law of Inertia”Also Known as “The Law of Inertia”Every object in a state of uniform motion tends to Every object in a state of uniform motion tends to remain in that state of motion unless an external force is remain in that state of motion unless an external force is

applied to it.applied to it.

Inertia put a planet in Inertia put a planet in motion and it will always motion and it will always

remain in motion unless remain in motion unless an external force acts an external force acts upon it.upon it.

Gravity pulls the planet Gravity pulls the planet towards the Sun to keep towards the Sun to keep it in orbit.it in orbit.

Newton's Second Law of Motion:Newton's Second Law of Motion:

The relationship The relationship between an between an object's mass object's mass mm, , its acceleration its acceleration a, and the a, and the applied force applied force FF is is F = maF = ma..

Newton's Third Law of Motion:Newton's Third Law of Motion:

For every action there is an For every action there is an

equal and opposite reaction.equal and opposite reaction. An equal and An equal and

opposite reaction.opposite reaction.