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Measuring Motion Speed, Velocity, and Acceleration

1: I can explain how to determine if an object is in motion. 2: I can differentiate between distance and displacement. 3: I can differentiate between

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Page 1: 1: I can explain how to determine if an object is in motion.  2: I can differentiate between distance and displacement.  3: I can differentiate between

Measuring Motion

Speed, Velocity, and Acceleration

Page 2: 1: I can explain how to determine if an object is in motion.  2: I can differentiate between distance and displacement.  3: I can differentiate between

Learning Targets 1: I can explain how to determine if an object is in

motion.

2: I can differentiate between distance and displacement.

3: I can differentiate between speed and velocity.

4: I am able to manipulate and use speed and velocity formulas to solve problems.

5: I can define acceleration.

6: I can use and manipulate the formula for acceleration to solve problems.

Page 3: 1: I can explain how to determine if an object is in motion.  2: I can differentiate between distance and displacement.  3: I can differentiate between

What is Motion?

Change in position in relation to a reference point or stationary object

Page 4: 1: I can explain how to determine if an object is in motion.  2: I can differentiate between distance and displacement.  3: I can differentiate between

Distance vs. Displacement

Distance follows the actual path Displacement is always a straight line http://maps.google.com/maps?hl=en&

q=Xenia&bav=on.2,or.r_gc.r_pw.r_qf.&bvm=bv.43148975,d.aWM&biw=1366&bih=622&wrapid=tlif136235527620010&um=1&ie=UTF-8&sa=X&ei=TuQzUf6yD8vryAGCm4CYAQ&ved=0CAgQ_AUoAg

Page 5: 1: I can explain how to determine if an object is in motion.  2: I can differentiate between distance and displacement.  3: I can differentiate between

Speed Speed is the distance traveled divided

by the time interval during which the motion occurred

Normally, objects do not travel at a constant speed

Average Speed - total distance total time

D

TS

Page 6: 1: I can explain how to determine if an object is in motion.  2: I can differentiate between distance and displacement.  3: I can differentiate between

Instantaneous vs. Average Speed

Page 7: 1: I can explain how to determine if an object is in motion.  2: I can differentiate between distance and displacement.  3: I can differentiate between

Speed Units

Will always be a distance unit / a time unit

› Ex. Cars: mi./h› Jets: km/h› Snails: cm/s› Falling objects: m/s

Page 8: 1: I can explain how to determine if an object is in motion.  2: I can differentiate between distance and displacement.  3: I can differentiate between

Calculating Speed What is the speed of a car that travels

30 miles in 2 hours?

How long will it take a car to go 220 miles traveling 55 mph?

If a car is traveling at 35 m/hr for 6 hours, how far will it travel?

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TS

15 mi/hr.

4 hours

210 miles

Page 9: 1: I can explain how to determine if an object is in motion.  2: I can differentiate between distance and displacement.  3: I can differentiate between

Graphing Speed

Page 10: 1: I can explain how to determine if an object is in motion.  2: I can differentiate between distance and displacement.  3: I can differentiate between

Graphing Speed: Distance vs. Time Graphs

Phoenix

Denver

Page 11: 1: I can explain how to determine if an object is in motion.  2: I can differentiate between distance and displacement.  3: I can differentiate between

Graphing Speed: Distance vs. Time Graphs

Speed = Slope = Rise/Run

Rise

Page 12: 1: I can explain how to determine if an object is in motion.  2: I can differentiate between distance and displacement.  3: I can differentiate between

Different Slopes

0

1

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5

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7

8

1 2 3 4 5 6 7

Time (hr)

Dis

tan

ce (

km

)

Run = 1 hr

Run = 1 hr

Run = 1 hr

Rise = 0 km

Rise = 2 km

Rise = 1 km

Slope = Rise/Run= 1 km/1 hr= 1 km/hr

Slope = Rise/Run= 0 km/1 hr= 0 km/hr

Slope = Rise/Run= 2 km/1 hr= 2 km/hr

Page 13: 1: I can explain how to determine if an object is in motion.  2: I can differentiate between distance and displacement.  3: I can differentiate between

Velocity Velocity is the speed of an object in a

particular direction Imagine two bicyclers leave the same

building at the same time. The both cycle at 10km/hr for 5 minutes. Why don’t they end up at the same place?

Page 14: 1: I can explain how to determine if an object is in motion.  2: I can differentiate between distance and displacement.  3: I can differentiate between

Calculating Velocity Same as speed, but also includes

direction Example:

› A plane travels south at 540 miles/hour.› Johnny walks 1 block/ minute towards the

school

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TV

Page 15: 1: I can explain how to determine if an object is in motion.  2: I can differentiate between distance and displacement.  3: I can differentiate between

Resultant Velocity The combination of two different velocities

acting at the same time+ =

- =

16 m/s15 m/s 1 m/s

15 m/s 14 m/s1 m/s

Page 16: 1: I can explain how to determine if an object is in motion.  2: I can differentiate between distance and displacement.  3: I can differentiate between
Page 17: 1: I can explain how to determine if an object is in motion.  2: I can differentiate between distance and displacement.  3: I can differentiate between

Acceleration

Acceleration is the rate at which velocity changes over time› An object accelerates if its speed, direction, or

both change Unit: m/s2

Average acceleration = final velocity – starting

velocitytime it takes to change

velocity

ΔV

Ta

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Acceleration and Velocity

As velocity increases, so does acceleration As velocity decreases, so does

acceleration When direction changes, so does

acceleration When there is a constant velocity, there is

no acceleration Increasing velocity - positive acceleration Decreasing velocity - negative acceleration-

deceleration

Page 19: 1: I can explain how to determine if an object is in motion.  2: I can differentiate between distance and displacement.  3: I can differentiate between

Acceleration and Velocity

Page 20: 1: I can explain how to determine if an object is in motion.  2: I can differentiate between distance and displacement.  3: I can differentiate between

Calculating Acceleration: Example

A roller coaster’s velocity at the top of a hill is 10m/s. Two sec later it reaches the bottom of the hill with a velocity of 26 m/s. What is the acceleration of the roller coaster?

Vf-Vo T 26-10 28 m/s/s

ΔV

Ta

Page 21: 1: I can explain how to determine if an object is in motion.  2: I can differentiate between distance and displacement.  3: I can differentiate between

Velocity vs. Time Graph Slope is the acceleration. A straight line is

constant acceleration

0

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0 1 2 3 4 5 6

Time (s)

Sp

ee

d (

m/s

)