Motion Motion Motion – Occurs when an object changes position relative to a reference point – Don’t have to see it move to motion took place

Motion Distance – Describes motion – How far did the object move? – SI unit is the meter (m) Distance vs Displacement Displacement – Distance and direction of an object’s change in position from the starting point

Speed – Distance an object travels per unit of time – Speed = distance ÷ time – s = d/t – Unit of measurement is meters/second (m/s)

Speed Formula =

Speed Word Problems SPEED = d/tTIME = d/sDISTANCE = s x t 1. If a car travels 400m in 20 seconds, how fast is it going? 2. How long did it take you to walk 100 meters if your speed is 2 m/s? 3. What is the distance traveled if you walk 1.5 m/s in 45 seconds?

Average Speed – Describes speed that’s changing – Total distance ÷ total time – S = d/t

Instantaneous Speed – Speed at a given point in time – Measured by speedometers

Velocity – Speed and the direction of an object – Velocity = distance ÷ time – How are speed and velocity different? Speed and Velocity

Distance/Time Graph

Acceleration – Rate of change of velocity (speed and direction) – Speeding up, slowing down and changing directions – Can be positive (+) or negative ( - ) – SI unit = m/s 2

Acceleration Formula A = acceleration V f = final velocity V i = initial velocity T = time

Acceleration Problems 1. A cars velocity changes from o m/s to 30 m/s in 10 seconds. Calculate acceleration. 2. If a speeding train hits the brakes and it takes the train 39 seconds to go from 54.8 m/s to 12 m/s what is the acceleration? 3. (Be careful!) How long will it take a car to go from 0 to 44 km/hr if they are accelerating at 5 km/hr 2 ? 4. In 1970, Don “Big Daddy” Garlits set what was then the world record for drag racing. He started at rest and accelerated at 16.5 m/s² (about 1.68 times free-fall acceleration) for 6.5 s. What was Garlits’s final speed?

Motion and Force Force – Push or a pull OR Does every force produce motion??

Force Net Force – Sum of two or more forces acting on an object Balanced Force – No motion Unbalanced Force – Motion

Inertia – The tendency of an object to resist any change in its motion – In motion, wants to stay at same speed and in same direction – At rest, wants to stay at rest

Newton’s First Law of Motion Newton’s 1 st Law – Object moving at a constant velocity keeps moving at that velocity unless an unbalanced force acts upon it – Law of Inertia – What are the unbalanced forces acting on the baseball that changes its motion?

Newton’s First Law In other words... – An object in motion stays in motion, an object at rest stays at rest, unless acted on by an unbalanced force

Why do we wear seatbelts?

Newton’s Second Law of Motion Newton’s 2 nd Law – The acceleration of an object is in the same direction as the net force and is inversely proportional to its mass – Shows relationship between force, mass and acceleration

Newton’s Second Law of Motion In other words... – An object will accelerate in the same direction as the force – The more massive an object, the slower it accelerates – The less massive, the faster it accelerates

Newton’s Second Law of Motion

Force = Mass x Acceleration

Standard Units of Force Force – Measured in Newtons (N) – 1 Newton = 1 Kg m/s 2 -Mass in Kg -Acceleration in m/s 2

What exactly is a Newton? pounds = 1 Newton of force 1 kN = lbs of force 4 Physical Science books=100 Newtons Jumbo jet = 3.4 million Newtons 150 pound person= about 668 Newtons

Newton’s Second Law Word Problems 1.If the mass of a helicopter is 4,500 kg and the net force on it is 18,000 N, what is the helicopter’s acceleration? 2.What is the net force on a dragster with a mass of 900 kg if its acceleration is 32 m/s 2 ? 3.A car is being pulled by a tow truck. What is the car’s mass if the net force on the car is 3,000 N and it has an acceleration of 2.0 m/s 2 ?

Forces 3 forces that oppose motion – Friction – Air Resistance – Gravity

Friction – force that opposes motion of two surfaces that are touching – Friction Friction 3 types of friction – Static – Sliding – Rolling

Static Friction – Force that prevents two surfaces from sliding – No motion – Caused by microwelds between two surfaces

Sliding Friction – Force that opposes the motion of two surfaces sliding past each other – Microwelds break and reform – Slows down motion

Rolling Friction – Force between a rolling object and the surface – Slows down motion

Friction What would happen if we had no frictional force between objects?

Air Resistance – Opposes motion of objects that move through the air – Depends on speed, size, and shape of object

Terminal Velocity – Falling at a constant speed – Highest speed a falling object will reach – Depends on size, shape and mass of object

Gravity – Attractive force between two objects – Depends on Masses of objects Distance between them – Isaac Newton formulated Law of Universal Gravitation

Gravity Gravitational Acceleration – Without air resistance, everything falls to Earth at 9.8 m/s 2 – So, acceleration due to gravity (g) = 9.8 m/s 2 – Force of gravity (N) = mass (kg) x acceleration of gravity (m/s 2 ) – F = m x g

Weight – Gravitational force exerted on an object – Weigh less on the moon – Weight (N) = mass (kg) x acceleration of gravity (m/s 2 ) – W = m x g

Mass Vs. Weight What is the difference in mass and weight? mass – amount of matter an object contains weight- force of gravity on an object

Centripetal Force Centripetal Acceleration – Acceleration toward the center of a curved path Centripetal Force – Net force exerted toward the center of a curved path

Newton’s Third Law of Motion Newton’s 3 rd Law – For every action, there is an equal and opposite reaction

Newton’s Third Law of Motion

Newton’s 3 Laws of Motion Newton's Laws of Motion Newton's Laws of Motion

Momentum – Property of moving objects – Product of the object’s mass and velocity – Momentum (p) = m x v – Linear Momentum Linear Momentum

Law of Conservation of Momentum – Momentum of objects do not change unless mass, velocity, or both change – Momentum can be transferred from object to object