Mix-Pair-Share

MotionSpeed, Velocity, & Acceleration

A. Motion

Motion: a change in position

How do you know something has changed position?

Frame of Reference: A point from which motion is determined

A. Motion

Reference point

Motion

A. Motion

Distance: The length of a path between two points. Unit: meter (m)

Displacement: The length from the starting point to the ending point (direction). Unit: meter (m)

Distance vs. Displacement

A. Motion

What is the runner’s distance?

What is the runner’s displacement & direction?

80 80 mm

20 m, North20 m, North

A. Motion

1. If Bob walks 100 meters East, 400 meters South, & 100 meters W, what is his distance and displacement?

2. If Suzy drives 2 miles North to the grocery store, then travels 1 mile South to the bank, and then 1 mile South back to her house, what is her distance and displacement?

A. Motion

3. What is the total distance traveled during the Indy 500? What is the total displacement?

4. A cross country runner leaves school for a 10-mile run. They end their run at a Dairy Queen one mile east from school. What is the total distance and displacement?

5. A delivery truck travels 18 blocks north, 10 blocks east, and 18 blocks south. What is the final displacement from the origin?

A. Motion

On your own sheet of paper to turn in…

Make up your own displacement problem. Write out the question completely, and solve it showing your own work.

B. Speed & Velocity

Speed: Distance ÷ Time.

Velocity: Speed in a specific direction (displacement) ~ Displacement ÷ Time.

distance/displacement: meter (m)time: second (s)

s-v

d

t÷

B. Speed & Velocity

1. Dave walks 200 meters in 40 seconds. What is his speed?

distance = 200 m

time = 40 s

speed = 200m/40s

= 5m/s

B. Speed & Velocity

2. Steve travels at 50m/s for 20s. How far does he go?

speed = 50m/s

time = 20s

distance = 50m/s*20s

= 1,000m

B. Speed & Velocity

3. How long would it take to run 100 meters if you run at 10m/s?

distance = 100m

speed = 10m/s

time = 100m/10m/s

= 10 s

B. Speed & Velocity

4. A runner completed the 100-meter dash in 10 seconds. Her average speed was?

5. A mail truck takes 20 second to move between mail boxes that are 10 meters apart. What is the average speed of the mail truck?

6. Laura covers 2km in 1,000 seconds. What is her speed?7. An object moves a distance of 10 meters in 5 seconds. What’s

the average speed?8. Susan drives her car at about 40m/s. How long does it take her

to drive 20km?9. Kim won a 300 meter race in 40 seconds. What was her rate of

speed?10. A car moved 60 meters west in 2 hours. What is its average

velocity?

B. Speed & Velocity

11. A moon rock is dropped from a cliff and it takes 2 seconds for the rock to fall 6.6 meters. What is the moon rock’s average speed?

12. A car travels 1000 meters in 5 seconds. What is its average velocity?

13. A baseball pitcher throws a fastball at 42 m/s. If the batter is 18m from the pitcher, approximately how much time does it take for the ball to reach the batter?

14. An object travels at a velocity of 19m/s for a time period of 16 s. How far did the object travel?

15. How far will a horse trot at a velocity of 4 m/s for 60 s?16. What is the difference between distance and displacement?17. Why do we not have velocity limits instead of speed limits?

Warm-Up – Write the Questions!!!

1. Draw the speed/velocity triangle.

2. What is the velocity of an object that traveled a total of 75m north in 125s?

3. How long would it take for a car to travel a distance of 200miles if it is traveling at a velocity of 55miles/hr?

B. Speed & Velocity

1. What distance did car A travel?

2. How much time did it take for car A to reach that distance?  

3. Average speed of car A?

4. How fast was A going at 1200m?

A

B

B. Speed & Velocity

5. What distance did car B travel?

6. How much time did it take for car B to reach that distance?

7. Average speed of car B?

8. How fast was B they going at 400m?

9. What happened to B between 10min-20min?

A

B

C. Acceleration

Acceleration occurs when an object accelerates (speeding up), decelerates (slowing down), or changes direction.

The rate at which velocity changes

C. Acceleration

Acceleration: velocity ÷ time.velocity: meter/second (m/s)time: second (s)Acceleration: meter/second/second (m/s/s or m/s2)

a

vf-vi

t÷

C. Acceleration

1.1. A roller coaster starts down a hill at 10 m/s. Three A roller coaster starts down a hill at 10 m/s. Three seconds later, its speed is 32 m/s. What is the roller seconds later, its speed is 32 m/s. What is the roller coastercoaster’’s acceleration?s acceleration?

Initial Velocity = 10m/sInitial Velocity = 10m/sFinal Velocity = 32 m/sFinal Velocity = 32 m/sTime = 3 sTime = 3 sAcceleration = (32-10)/3Acceleration = (32-10)/3

= 7.3 m/s= 7.3 m/s22

C. Accleration

2. How long will it take a car traveling 30 m/s to come to a stop if its acceleration is -3 m/s2?

Initial Velocity = 30m/s

Final Velocity = 0 m/sAcceleration = -3m/s2

Time = (0-30)/-3 = 10s

Practice3.3. A skater goes from a standstill to a speed of 6.7 m/s in 12 A skater goes from a standstill to a speed of 6.7 m/s in 12

seconds. What is the acceleration of the skater? seconds. What is the acceleration of the skater? 4.4. During a race, a sprinter increases from 5.0 m/s to 7.5 m/s over During a race, a sprinter increases from 5.0 m/s to 7.5 m/s over

a period of 1.25s. What is the sprintera period of 1.25s. What is the sprinter’’s average acceleration s average acceleration during this period?during this period?

5.5. As a shuttle bus comes to a normal stop, it slows from 9.00m/s As a shuttle bus comes to a normal stop, it slows from 9.00m/s to 0.00m/s in 5.00s. Find the average acceleration of the bus. to 0.00m/s in 5.00s. Find the average acceleration of the bus.

6.6. A bicyclist accelerates at 0.89m\sA bicyclist accelerates at 0.89m\s22 during a 5.0s interval. What is during a 5.0s interval. What is the change in the speed of the bicyclist and the bicycle? the change in the speed of the bicyclist and the bicycle?

7.7. MarisaMarisa’’s car accelerates at an average rate of 2.6m/ss car accelerates at an average rate of 2.6m/s22. Calculate . Calculate how long it takes her car to accelerate from 24.6m/s to 26.8m/s.how long it takes her car to accelerate from 24.6m/s to 26.8m/s.

8.8. If a rocket undergoes a constant total acceleration of 6.25m/sIf a rocket undergoes a constant total acceleration of 6.25m/s22, , so that its speed increases from rest to about 750m/s, how long so that its speed increases from rest to about 750m/s, how long will it take for the rocket to reach 750m/s. will it take for the rocket to reach 750m/s.

0.56m/s2

-

C. Acceleration

Specify the time period Specify the time period when the object was...when the object was...

• slowing downslowing down– 5 to 10 seconds5 to 10 seconds

• speeding upspeeding up– 0 to 3 seconds0 to 3 seconds

• moving at a constant moving at a constant speedspeed– 3 to 5 seconds3 to 5 seconds

• not movingnot moving– 0 & 10 seconds0 & 10 seconds

0

1

2

3

0 2 4 6 8 10

Time (s)

Sp

ee

d (

m/s

)

Speed-Time Graph

C. Acceleration

What is the acceleration between:

1.0-2s?

2.2-3s?

3.3-5s?

4.5-10s?0

1

2

3

0 2 4 6 8 10

Time (s)

Sp

ee

d (

m/s

)

Speed-Time Graph