Motion and AccelerationMotion and AccelerationNotesNotes

Chapter 2 Chapter 2

Section 1 and 2Section 1 and 2

Key TermsKey TermsDistanceDistance

How far an object has movedHow far an object has movedDisplacementDisplacement

The distance The distance ANDAND direction of an direction of an object’s change in positionobject’s change in position from the from the starting pointstarting point

SpeedSpeedThe distance an object travels per The distance an object travels per

unit of timeunit of times=d/ts=d/t

Key TermsKey Terms Average SpeedAverage Speed

Is the Is the total distancetotal distance traveled divided traveled divided by the by the total timetotal time of travel of travel

Instantaneous SpeedInstantaneous SpeedIs the speed at a given point in timeIs the speed at a given point in time

VelocityVelocityDescribes the speed Describes the speed andand direction of direction of

an objectan objectMomentumMomentum

The product of an objects mass and velocityThe product of an objects mass and velocityEquation (p=mv)Equation (p=mv)

Motion ReviewMotion ReviewWhat is the difference between motion What is the difference between motion

and displacement?and displacement?Motion involves the change in Motion involves the change in

position relative to a reference point position relative to a reference point and displacement involves the and displacement involves the change in position AND the direction change in position AND the direction of the movementof the movement

SpeedSpeedRateRate

Any change over timeAny change over timeEquationEquation

Speed=distance/timeSpeed=distance/timeA speed that doesn’t change over timeA speed that doesn’t change over time

Constant speedConstant speedA speed that DOES changeA speed that DOES change

Changing speedChanging speed

SpeedSpeedHow do constant speed and changing How do constant speed and changing

speed differ?speed differ?At a constant speed, an object’s At a constant speed, an object’s

instantaneous speed remains the instantaneous speed remains the same, but at changing speed, an same, but at changing speed, an object’s instantaneous speed variesobject’s instantaneous speed varies

Examples: Examples: Driving a carDriving a car

Speed ReviewSpeed ReviewAverage SpeedAverage Speed

Speed of motion when speed is changingSpeed of motion when speed is changingEquation for Avg SpeedEquation for Avg Speed

Speed=TOTAL distance/TOTAL timeSpeed=TOTAL distance/TOTAL time Instantaneous SpeedInstantaneous Speed

Speed at any given point in timeSpeed at any given point in time

Velocity Vs. SpeedVelocity Vs. SpeedRace Car animationRace Car animation

Calculations of Speed and Calculations of Speed and velocityvelocity

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Practice problem #1Practice problem #1

An object travels 345 km in 6.5 hours. An object travels 345 km in 6.5 hours. What is the speed of the objectWhat is the speed of the object

Practice Problem #2Practice Problem #2

A car traveling at 65 miles/hour completes A car traveling at 65 miles/hour completes a trip in 5.0 hours. How far did the car a trip in 5.0 hours. How far did the car travel?travel?

Practice Problem # 3Practice Problem # 3

A boat is moving 65 km/hr and travels 60 A boat is moving 65 km/hr and travels 60 km. How long did it take?km. How long did it take?

Distance-time GraphDistance-time Graph

Plot distance on a __________ axisPlot distance on a __________ axisVerticalVertical

Plot time on a ____________ axisPlot time on a ____________ axisHorizontalHorizontal

PurposePurposeTo show the change in distance related to To show the change in distance related to

change in timechange in time

Distance-Time GraphDistance-Time GraphDistance vs Time

Dis

tan

ce (

m)

Time (s)

Units…..Units…..SpeedSpeed

Miles/hour; miles/minute; km/s; m/s Miles/hour; miles/minute; km/s; m/s etcetc

TimeTimeSecond, minute, hour, days etcSecond, minute, hour, days etc

DistanceDistanceMiles, km, meters, cm etcMiles, km, meters, cm etc

AccelerationAccelerationm/sm/s22; km/s; km/s22, miles/second/second, miles/second/second

ACCELERATIONACCELERATION

AccelerationAccelerationDefinitionDefinition

Change in velocity’s rateChange in velocity’s ratePositive accelerationPositive acceleration

Speed is increasingSpeed is increasingNegative accelerationNegative acceleration

Speed is decreasingSpeed is decreasing

An Object is accelerating…An Object is accelerating…IF it changes speed IF it changes speed OROR direction directionExample:Example:A car going 60 mph increases in speed to A car going 60 mph increases in speed to

70 mph as it gets onto the highway. Is it 70 mph as it gets onto the highway. Is it accelerating?accelerating?YESYES

A car staying at a constant speed of 70 A car staying at a constant speed of 70 mph in a circle. Is it accelerating?mph in a circle. Is it accelerating?YESYES

Calculating Calculating AccelerationAccelerationEquationEquation

Change in velocity/timeChange in velocity/timeChange in velocity=final Change in velocity=final

velocity-initial velocityvelocity-initial velocityUnit for accelerationUnit for acceleration

Meters per second squared Meters per second squared (m/s(m/s22))

Calculations of AccelerationCalculations of Acceleration

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The physics ClassroomThe physics Classroom

Acceleration Vs. VelocityAcceleration Vs. Velocity

Practice Problem #1Practice Problem #1

Falling objects drop with an average Falling objects drop with an average acceleration of 9.8 m/s/s (m/s2). If an acceleration of 9.8 m/s/s (m/s2). If an object falls from a tall building, how long object falls from a tall building, how long will it take before it reaches a speed of 49 will it take before it reaches a speed of 49 m/sm/s

Practice Problem #2Practice Problem #2

A bus moving at 25 km/hr comes to a stop A bus moving at 25 km/hr comes to a stop in 10 seconds. What is its acceleration?in 10 seconds. What is its acceleration?

Practice Problem #3Practice Problem #3

A driver starts his parked car and within 5 A driver starts his parked car and within 5 seconds reaches a velocity of 54 km/hr as seconds reaches a velocity of 54 km/hr as he travels east. What is his acceleration?he travels east. What is his acceleration?

Practice problem #4Practice problem #4

If an airplane accelerates at 50 If an airplane accelerates at 50 meters/second/second, how much does its meters/second/second, how much does its speed change in 3 seconds?speed change in 3 seconds?