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Wednesday, April 19, 2023

Oh, WaitOh, Wait

MotionMotion

Chapter 6Chapter 6

Section 1Section 1

What is Motion?What is Motion?A Change in PositionA Change in Position

Motion…Motion…

Distance and Distance and DisplacementDisplacement Distance – How far you have Distance – How far you have

traveledtraveled Displacement – How far away it isDisplacement – How far away it is

Distance Verses Distance Verses DisplacementDisplacement

Texas Motor SpeedwayTexas Motor Speedway

1.5 mile oval

Distance Vs Distance Vs DisplacementDisplacement If a driver goes 200 laps starting If a driver goes 200 laps starting

at the start line and finishing at at the start line and finishing at the finish line;the finish line;

What is the distance traveled?What is the distance traveled? What is the displacement?What is the displacement?

AnswerAnswer

The distance traveled is 300 miles The distance traveled is 300 miles (200 laps X 1.5 miles per lap)(200 laps X 1.5 miles per lap)

The displacement is zero. (The The displacement is zero. (The driver is at the same location he driver is at the same location he started from.)started from.)

Relative motionRelative motion

An object in motion changes An object in motion changes positionposition

This position is in relation to This position is in relation to another objectanother object

SpeedSpeed

Two factors determine speedTwo factors determine speed– Distance traveledDistance traveled– Time spent travelingTime spent traveling– Examples;Examples;

Miles per hourMiles per hour Feet per secondFeet per second Meters per secondMeters per second

Speed is distance divided by timeSpeed is distance divided by time

SpeedSpeed

So…So…

DistanceTime =

Speed

And…And…

Distance = Speed Time

Constant SpeedConstant Speed

Cruise control set at 60 MPHCruise control set at 60 MPH Always at the same speedAlways at the same speed Covering one mile every minuteCovering one mile every minute

– Same distance each time intervalSame distance each time interval

Key term CONSTANT!Key term CONSTANT!

Average SpeedAverage Speed

Total time divided by total distance.Total time divided by total distance. RMS to Six Flags 20 minutes.RMS to Six Flags 20 minutes. 13 miles 20 minutes.13 miles 20 minutes. Constant Speed?Constant Speed? No… stop signs, freeways, city No… stop signs, freeways, city

streets.streets. Different rates of speed.Different rates of speed. This is average speed.This is average speed.

What is Our Speed?What is Our Speed?

13 miles13 miles 20 minutes = .33 hours20 minutes = .33 hours 13 Miles/0.33 Hours = 39.4 M/H 13 Miles/0.33 Hours = 39.4 M/H

or MPHor MPH

VelocityVelocity

What is the difference between What is the difference between velocity and speed?velocity and speed?

Velocity has direction, speed does notVelocity has direction, speed does not Remember displacement and Remember displacement and

distance?distance? Speed is distance divided by timeSpeed is distance divided by time Velocity is displacement divided by Velocity is displacement divided by

timetime

OR…OR…

Δ (delta) is science speak for change in something

CalculationCalculation

A Sprinter runs a 100 meter race A Sprinter runs a 100 meter race in 10 secondsin 10 seconds

What is his average velocity?What is his average velocity? Distance is 100 meters Distance is 100 meters Time is 10 secondsTime is 10 seconds 100Meters 100Meters ÷ 10 Seconds = 10M/S÷ 10 Seconds = 10M/S

Texas Motor SpeedwayTexas Motor Speedway

1.5 mile oval

Velocity vs. SpeedVelocity vs. Speed

If a driver goes 200 laps starting If a driver goes 200 laps starting at the start line and finishing at at the start line and finishing at the finish line in 2 Hoursthe finish line in 2 Hours

What is his speed?What is his speed? What is his velocity?What is his velocity?

Answer Answer

SpeedSpeed 300 Miles (distance)/2 Hours = 300 Miles (distance)/2 Hours =

150 MPH150 MPH VelocityVelocity 0 (displacement)/2 Hours = 0MPH0 (displacement)/2 Hours = 0MPH

AccelerationAcceleration

A change in velocityA change in velocity Speeding up or slowing downSpeeding up or slowing down Acceleration equals final velocity Acceleration equals final velocity

minus initial velocity divided by timeminus initial velocity divided by time

OROR

CalculationCalculation

A skateboarder goes from 2 m/s to A skateboarder goes from 2 m/s to 8 m/s in 12s. What is his 8 m/s in 12s. What is his accelerationacceleration

Initial velocity = 2m/sInitial velocity = 2m/s Final velocity = 8m/sFinal velocity = 8m/s Time is 12sTime is 12s So So ΔΔV = V = 8m/s - 2m/s = 6m/s8m/s - 2m/s = 6m/s 6ms 6ms ÷ 12s = 0.5m/s/s or 0.5m/s÷ 12s = 0.5m/s/s or 0.5m/s22

CalculationCalculation

Same skateboarder hits a mud hole Same skateboarder hits a mud hole and goes to a complete stop in 1s. and goes to a complete stop in 1s. What is his accelerationWhat is his acceleration

Initial velocity = 8m/sInitial velocity = 8m/s Final velocity = 0m/sFinal velocity = 0m/s Time is 1sTime is 1s So… So… ΔΔV = V = 0m/s - 8m/s = -8m/s0m/s - 8m/s = -8m/s -8ms -8ms ÷ 1s = -8m/s/s or ÷ 1s = -8m/s/s or -8m/s-8m/s22

TurningTurning

Remember velocity has direction.Remember velocity has direction. So a change in direction is also So a change in direction is also

accelerationacceleration

Texas Motor SpeedwayTexas Motor Speedway

1.5 mile oval

QuestionQuestion

If a racecar is traveling at a If a racecar is traveling at a constant speed at Texas Motor constant speed at Texas Motor Speedway, is it accelerating?Speedway, is it accelerating?

Yes, on the turns.Yes, on the turns.

Three Ways to Three Ways to AccelerateAccelerate

1.1. Increase velocityIncrease velocity

2.2. Decrease velocityDecrease velocity

3.3. Change directionChange direction

THE ENDTHE END