Describing and Measuring Motion

1
Table of Contents

• Describing and Measuring Motion
• Slow Motion on Planet Earth
• Acceleration

2
Learning Objectives

• Determine when an object is in motion.
• Key terms reference point, relative motion,
  displacement
• Calculate an objects speed and velocity.
• Key terms average speed, instant speed, speed
  direction, velocity
• Demonstrate how to graph motion.
• Key terms slope rise/run rise divided by run
  vertical movement divided by horizontal
  movement on a graph

3
Graphing Motion Experiment (Part 1)

• Goal- To create 4 distance vs. time graphs that
  correspond to the 4 below. Distance (d) is on
  the y-axis.
• Background- What is your reference point for this
  experiment? (What are you measuring the distance
  from?)
• Hypothesis- Describe how you think you will need
  to move for EACH of the 4 distance-time graphs.

1
2
3
4
d (m)
Time (s)
Time (s)
Time (s)
Time (s)
4
Graphing Motion Experiment (Part 1)

• Results- Sketch your distance-time graphs and
  describe how you moved for each line segment of
  the graph.
• Conclusion- In complete sentences and using the
  motion sensor as your reference point, describe
  how you would move (or not move) for
• A horizontal line on a distance-time graph.
• A slanted line going down and to the right on a
  distance-time graph.
• A curved line curving up and to the right on a
  distance-time graph.
• What happens to the slope of the graph if a
  person moves faster?
• What does the graph look like if a person is
  moving at a constant rate or speed?

5
Learning Objectives

• Determine when an object is in motion.
• Key terms reference point, relative motion,
  displacement
• Calculate an objects speed and velocity.
• Key terms average speed, instant speed, speed
  direction, velocity
• Demonstrate how to graph motion and how to
  interpret the graph.
• Key terms slope rise/run rise divided by run
  vertical movement divided by horizontal
  movement on a graph

6
Determining When an Object is in Motion
- Describing and Measuring Motion

• Have you ever watched a large truck pass you on
  the highway and felt like you were going
  backwards?
• Whether or not an object is in motion depends on
  the reference point you choose if the distance
  between the object and the reference point is
  changing.

Figure 2- Page 8
7
Negative Distance Football

• Question Can a distance be negative in
  relationship to a reference point?
• Football Example Reference point in football
  (below), positive play (right), negative play-
  sacked for a loss (bottom right)

8
Which of the following is true if you are riding
your bike past the middle school?

1. You are moving relative to the bike, but not the
   school.
2. You are not moving relative to the school or the
   bike.
3. You are moving relative to the school, but not
   relative to the bike.
4. You are moving relative to the bike and the
   school.

9
Suppose you are driving, and you are pulled over
by a cop. The cop explains that his radar gun
measured you as going 30 mph in a 65 mph zone.
He also tells you that he used his radar gun
while driving down the highway. Using physics,
how do you get out of getting a ticket for
driving too slowly?

1. Explain that he graduated from Penns Valley.
2. Explain that since he was moving, your speed is
   relative to his speed. This makes it seem like
   you were driving slowly.
3. Explain that since he was moving, your speed is
   relative to his speed. This makes seem like you
   were driving fast.
4. Explain that you never drive slowly. You always
   drive fast.

10
How would a position-time graph appear for an
object at that is not moving?

1. A straight horizontal line
2. A slanted line moving up and to the right.
3. A curved line curving up and to the right.
4. A slanted line moving down and to the left.

11
Which of the following distance-time graphs shows
a person moving closer to a reference point?

1. Graph 1
2. Graph 2
3. Graph 3
4. None of the graphs below.

1
2
3
d (m)
Time (s)
Time (s)
Time (s)
12
Which of the following shows a person moving at a
constant rate?

1. Graph 1 only.
2. Graph 2 only.
3. Graph 3 only.
4. Graphs 1 2.
5. Graphs 1, 2, and 3.

1
2
3
d (m)
Time (s)
Time (s)
Time (s)
13
Which of the following shows a person moving the
fastest away from the reference point?

1. Graph 1
2. Graph 2
3. Graph 3
4. None of the above.

2
3
1
d (m)
Time (s)
Time (s)
Time (s)
14
Calculating Speed
- Describing and Measuring Motion

• What is an example of a speed that a fast car can
  go?
• So, how can you calculate speed? If you travel
  45 km in 3 hours, what is your average speed?
• Speed change in distance/change in time
• Instant speed is your speed at a certain time.
• Average speed is your averaged speed for the
  ENTIRE trial, event, or race.
• Avg. speed change in distance/change in time

15
Speed vs. Velocity Experiment

• Scenario (do not need to write) Markie is
  jogging at 6.0 mph, while Suzy is also jogging at
  6.0 mph. However, Markies velocity is -6.0 mph
  while Suzys is 6.0 mph. Why are their speeds
  the same, but their velocities are different?
• Goal Determine the difference between SPEED and
  VELOCITY.
• Hypothesis What do you think is the difference
  between speed and velocity?
• General Procedure (Handheld procedure done as a
  group beforehand)
• Using the velocity-time graphs (x,y) coordinates
  at the top of the graph screen, determine each
  persons VELOCITY while moving away from the
  motion sensor. Be sure to check if the velocity
  is positive or negative.
• Using the velocity-time graphs (x,y) coordinates
  at the top of the graph screen, determine each
  persons VELOCITY when moving back toward the
  motion sensor. Be sure to check if the velocity
  is positive or negative.
• Results Organize the VELOCITIES FOR EACH PERSON
  in a DATA TABLE.

16
Speed vs. Velocity Experiment

• Conclusion (answer in complete sentences)
• Were there any negative velocities? Why is this
  the case? Is velocity just speed? If not, what
  else is factored in to velocity? Hint- Think
  about when your velocity was negative relative to
  the motion sensor, and keep in mind that speed is
  NEVER negative.
• Scenario Markie is jogging at a speed of 6.0
  mph, while Suzy is also jogging at a speed of 6.0
  mph. However, Markies velocity is -6.0 mph
  while Suzys is 6.0 mph. Why are their speeds
  the same, but their velocities are different?
• Velocity speed direction relative to a
  reference point
• So, Markie was going just as fast as Suzy, but in
  the opposite direction.

Peregrine Falcons can dive at speeds up to 242
mph.
17
Graphing Motion (Calculating speed)
- Describing and Measuring Motion

• You can show the motion of an object on a line
  graph in which you plot distance versus time.
  Remember Velocity is the change in distance in a
  certain direction during a certain length of
  time. So, velocity or speed rise/run

18
Graphing Motion Experiment (Part 2)

• In your lab notebook, match up each of the 4
  distance-time graphs with one of the velocity
  graphs below. Sketch each of the graphs below
  and designate which velocity-time graph
  corresponds to which distance-time graph.
• Use your descriptions of speed or rate from
  Graphing Motion (Part 1) for help.
• BE SURE TO CAREFULLY ANALYZE WHAT HAPPENED TO
  DISTANCE DIRECTION AND WHAT IS HAPPENING TO
  VELOCITY FOR THE DURATION OF DATA COLLECTION TIME
  FRAME! V velocity

A
B
C
D
V (m/s)
Time (s)
19
Graphing Motion Experiment (Parts 1 2)
1
2
3
4
d (m)
Time (s)
Time (s)
Time (s)
Time (s)
A
B
D
C
V (m/s)
Time (s)
20
Distance Determination (from a Speed-Time Graph)
5 m/s
SPEED (m/s)
1 s
2 s
Time (s)

• How far will the object have gone in 2 seconds?
• 10 meters (5 m/s x 2 s)
• Or
• Determine the area under the line Create a
  rectangle and determine its area (l x w 2 s x 5
  m/s 10 m)

21
Jebediah runs 6 miles in 1 hour (60 minutes).
His average speed is 6 mph. However, at minute
45, his speed was 4.5 mph. Which of the
following would best explain what happened?

1. He was probably running faster at minute 45 than
   he was for most of the jog.
2. He got more energy from drinking 5 Red Bulls
   before jogging.
3. He was running up a hill and had to slow down.
4. He wore out his running shoes.

22
Explain what happened between 0 and 4 minutes in
terms of the persons speed. Keep in mind, the
graph is a DISTANCE-TIME graph.

1. The person moved at a constant speed
2. The person stopped moving.
3. The person slowed down.
4. The person moved faster.

23
What is the velocity of the object based upon the
data in the graph below? Assume time is in
seconds.

1. 50 m/s
2. 10 m/s
3. 5 m/s
4. 50 m

24
How is velocity different from speed?

1. Velocity involves instant and average speed, so
   it will be positive.
2. Speed involves direction as well, so it can be
   negative.
3. Theyre the same.
4. Velocity involves direction as well, so it can be
   negative.

25
Which of the following may only be a measurement
of speed?

1. -0.001 mm/s
2. -2 m/s
3. 27 mph
4. 100 km/h East

26
Which of the following is a measurement of
velocity?

1. 32 rpm (revolutions per minute) clockwise
2. 100 km/h Northeast
3. -2.7 m/s
4. All of the above.

27
Suzy is moving East at a velocity of 7 mph from
her house. Markie moved 14 miles West from
Suzys house in 2 hours. What is Markies
velocity?

1. 7 mph
2. -7 mph
3. 6 mph East
4. -6 mph

28
If you are running at 5 mph, then how far will
you run in 4 hours at the same pace?

1. 25 miles
2. 5 mph
3. 20 miles
4. 15 miles

29
How far will the object go in 4 seconds (using
the graph below)?

1. 0 meters
2. 4 meters
3. 8 meters
4. 12 meters

2 m/s
SPEED (m/s)
2 s
4 s
6 s
Time (s)
30
Noggin Knockers from p. 15- 1a, 1c, 2b, 2c, 3a,
3b 9 points- Homework Grade

• 1- (a) Car- not moving
• (b) Road- not moving since the distance between
  you and the road is not changing
• (c) Stop Sign- moving away or toward it. (1
  point per part for 3 points total).
• 2- Velocity speed direction (2 points)
• 3- Slope and Speed 600 meters/3 minutes 200
  m/min (2 points- 1 point for the correct value, 1
  point for the correct units).
• 4- Distance Speed x time area under the line
  10 m/s x 3 s 30 m (2 points- 1 point for
  value, 1 point for correct units)

31
Softball vs. Baseball Reaction Times

• Big Question Is it tougher to hit a baseball
  than a softball?
• Baseball data
• 95 mph fastball 139.33 ft/.sec.
• Distance from the pitchers mound 60.5 ft.
• Time it takes ball to get to the plate (t) ?
• Set up a proportion (t time) 1 sec. / 139.33
  ft. t / 60.5 ft.
• t .434 seconds
• Note that it is slightly more time than the
  actual reaction time because the pitcher launches
  the ball about 5.5 feet in front of the mound!
• Once this release point is taken into account,
  the reaction time is 0.395 seconds.

32
Softball vs. Baseball Reaction Times

• Big Question Is it tougher to hit a baseball
  than a softball?
• Softball data
• 72 mph softball 105.6 ft/.sec.
• Distance from the pitchers mound 43 ft.
• Time it takes ball to get to the plate (t) ?
• Set up a proportion (t time) 1 sec. / 105.6
  ft. t / 43 ft.
• t .407 seconds
• Note that it is slightly more time than the
  actual reaction time because the pitcher launches
  the ball about 6 feet in front of the mound!
• Once this release point is taken into account,
  the reaction time is 0.350 seconds.

33
Graph Matching (No lab write-up)

• Goal- Determine who can match the graph the best
  and how they were able to do it.

34
End of SectionDescribing and Measuring Motion
35
Earths Plates
- Slow Motion on Planet Earth

• According to the theory of plate tectonics,
  Earths landmasses have changed position over
  time
• because they are part of plates that are slowly
  moving.

36
Plate Movement
- Slow Motion on Planet Earth

• Some plates move at a rate of several centimeters
  each year. Others move only a few millimeters per
  year.

37
Continental Drift Activity
- Slow Motion on Planet Earth

• Click the Active Art button to open a browser
  window and access Active Art about continental
  drift.

38
Previewing Visuals
- Slow Motion on Planet Earth

• Before you read, preview Figure 8. Then write two
  questions that you have about the diagram in a
  graphic organizer like the one below. As you
  read, answer your questions.

Previewing Figure 8
Q. How have the positions of the continents
changed over time?
A. The distance between the continents has
increased.
Q. What causes Earths plates to move?
A. Slow-moving currents beneath Earths outer
layer cause the plates to move.
39
End of SectionSlow Motion on Planet Earth
40
Learning Objectives

• Describe the motion of an object as it
  accelerates.
• Key Terms acceleration, change in velocity
  over time, increasing vs. decreasing speed,
  change in direction
• Calculate acceleration.
• Key Terms change in velocity over time
• Describe how graphs are used to analyze the
  motion of an accelerating object.
• Key Terms Velocity vs. Time graph, Distance vs.
  Time Graph, slope

41
Calculating Acceleration
- Acceleration

• What does it mean if a car accelerates? Have you
  ever heard of a car that can go 0 to 60 mph in
  about 6 seconds? (Just like mine). What about
  when a car decelerates?
• To determine the acceleration of an object moving
  in a straight line, you must calculate the change
  in velocity per unit of time
• Average Acceleration (final velocity starting
  velocity)/time

42
Graphing Acceleration
- Acceleration

• You can use both a speed-versus-time graph and a
  distance-versus-time graph to analyze the motion
  of an accelerating object.

43
Velocity vs. Acceleration Experiment

• Goal Create the 3 velocity-time graphs below
  and determine which acceleration vs. time graphs
  they correspond to. Keep in mind that your graphs
  will be more rigid, but the general pattern
  should be the same.
• Hypothesis Determine how you think you should
  move for EACH of the 3 graphs (BY ONLY MOVING
  AWAY).
• Results Sketch your velocity-time graphs (hit
  the F2 button once and press up to adjust the
  scale), describe how you moved for each one, and
  match them up with the correct acceleration vs.
  time graphs. Use your descriptions for help.

III
I
II
V (m/s)
Time (s)
Time (s)
Time (s)
44
Velocity vs. Acceleration Experiment
B
A
A (m/s2)
C
0
0
0
Time (s)

• Conclusion (answer in complete sentences)
• How did you move for 0 or no acceleration?
• How did you move for a constant positive
  acceleration?
• How did you move for a constant negative
  acceleration (or deceleration)?
• What is the independent or manipulated variable
  for the graphs above? What is the dependent or
  responding variable for the graphs above? Also,
  note which axis (x or y) the variables are on.

45
Velocity vs. Acceleration Match-Up
B
C
A
A (m/s2)
0
0
0
Time (s)
II
I
III
V (m/s)
Time (s)
Time (s)
Time (s)
46
Learning Objectives

• Describe the motion of an object as it
  accelerates.
• Key Terms acceleration, change in velocity
  over time, increasing vs. decreasing speed,
  change in direction
• Calculate acceleration.
• Key Terms change in velocity over time
• Describe how graphs are used to analyze the
  motion of an accelerating object.
• Key Terms Velocity vs. Time graph, Distance vs.
  Time Graph, slope

47
Graphing Acceleration
- Acceleration

• You can use both a speed-versus-time graph and a
  distance-versus-time graph to analyze the motion
  of an accelerating object.

48
Calculating Acceleration
- Acceleration

• To determine the acceleration of an object moving
  in a straight line, you must calculate the change
  in velocity per unit of time.
• Average Acceleration (final velocity starting
  velocity)/time

49
Calculating Acceleration
- Acceleration

• As a roller-coaster car starts down a slope, its
  speed is 4 m/s. But 3 seconds later, at the
  bottom, its speed is 22 m/s. What is its average
  acceleration?
• Read and Understand
• What information have you been given?
• Initial speed 4 m/s
• Final Speed 22 m/s
• Time 3 s

50
Calculating Acceleration
- Acceleration

• As a roller-coaster car starts down a slope, its
  speed is 4 m/s. But 3 seconds later, at the
  bottom, its speed is 22 m/s. What is its average
  acceleration?
• Plan and Solve
• What quantity are you trying to calculate?
• The average acceleration of the roller-coaster
  car __
• What formula contains the given quantities and
  the unknown quantity?
• Acceleration (Final speed Initial
  speed)/Time
• Perform the calculation.
• Acceleration (22 m/s 4 m/s)/3 s 18 m/s/3 s
• Acceleration 6 m/s2
• The roller-coaster cars average acceleration is
  6 m/s2.
• This is a positive acceleration (speeding up).

51
Calculating Acceleration
- Acceleration

• As a roller-coaster car starts down a slope, its
  speed is 4 m/s. But 3 seconds later, at the
  bottom, its speed is 22 m/s. What is its average
  acceleration?
• Look Back and Check
• Does your answer make sense?
• The answer is reasonable. If the cars speed
  increases by 6 m/s each second, its speed will be
  10 m/s after 1 second, 16 m/s after 2 seconds,
  and 22 m/s after 3 seconds.

52
Calculating Acceleration
- Acceleration

• Practice Problem
• A certain car brakes from 27 m/s to rest in 9
  seconds. Find the cars average acceleration.

• (0 m/s 27 m/s ) 9 s -27 m/s 9 s -3 m/s2
• This is a negative acceleration, which is also
  called a deceleration (slowing down)

53
Acceleration Practice Problems Determine Each
Objects Acceleration

• A car travels at 28 m/s (a little over 60 mph)
  and stops at a red light in 4 seconds.
• A person starts jogging at 6 km/h and ends up
  jogging at 10 km/h in 30 minutes. You may need
  to convert units.
• Your car goes from rest to 30 m/s in half a
  minute.

54
Noggin Knockers
55
Noggin Knockers
56
Noggin Knockers
57
Learning Objectives

• Describe the motion of an object as it
  accelerates.
• Key Terms acceleration, change in velocity
  over time, increasing vs. decreasing speed,
  change in direction
• Calculate acceleration.
• Key Terms change in velocity over time
• Describe how graphs are used to analyze the
  motion of an accelerating object.
• Key Terms Velocity vs. Time graph, Distance vs.
  Time Graph, slope

58
Changing Directions

• When riding in a car, have you ever changed
  directions by going around a curve or turn in the
  road at a high speed? Did you feel your body
  push towards the outside of the curve?
• Another example would be riding on those
  amusement park rides that spin around quickly.
• This is an acceleration too (Centripetal
  Acceleration the object youre in is being
  pulled towards the middle of the circle while you
  feel pushed toward the outside of the circle).

59
Which of the following is not an example of a
positive or negative acceleration?

1. Going from jogging to running during the last 30
   seconds of a 5K race.
2. Jebediah rides his horse and buggy at a constant
   speed of 5 mph for an entire 10 minutes on a
   straight road.
3. A car braking due to traffic.
4. A car turning around on the highway.

60
Which of the following is an example of a
positive acceleration?

1. A bus coming to a stop.
2. A car peeling out of the parking lot like Mr.
   Snyder on Fridays at 315 PM.
3. A rollercoaster braking.
4. A person standing still.

61
Which of the following is an example of a
negative acceleration?

1. A skateboarder taking off from rest to a speed of
   5 m/s.
2. A truck going at a constant speed of 65 mph.
3. A bus coming to a stop after a tractor stops in
   front of it.
4. A car speeding up in the passing lane.

62
Which of the following is an example of 0 or no
acceleration?

1. A bowling ball slowing down when it hits the 10
   pins.
2. A car speeding up to pass another vehicle.
3. A bus coming to a stop.
4. A person riding a bike at 15 mph for 2 hours on a
   straight path because there is nothing better to
   do in Bald Eagle.

63
Determine the acceleration of the object from the
graph below.

1. 6 m/s/s
2. 2 m/s/s
3. 10 m/s/s
4. 5 m/s/s

64
If you measure velocity in miles per hour and
time in hours, then what would be the units for
acceleration?

1. Miles per hour per hour (Miles/h/h or
   Miles/hr/hr)
2. Miles per hour (mph)
3. Hours (h or hr)
4. Hours squared per mile (hr2/mile)

65
Determine the acceleration if a roller coaster
starts from rest and reaches a speed of 27 m/s in
3 seconds.

1. 9 m/s or 9 mps
2. -81 m/s/s or -81 m/s2
3. 9 m/s/s or 9 m/s2
4. -9 m/s/s or -9 m/s2

66
A roller coaster goes from a speed of 27 m/s to
rest in 3 seconds. What is the rollercoasters
acceleration?

1. 9 m/s or 9 mps
2. -81 m/s/s or 81 m/s2
3. 9 m/s/s or 9 m/s2
4. -9 m/s/s or -9 m/s2

67
A car is traveling at 20 mph and after 10
seconds, the car is moving at 20 mph. What is
its average acceleration?

1. -2 m/s/s or -2 m/s2
2. 2 m/s/s or 2 m/s2
3. 0 m/s/s or 0 m/s2
4. It cannot be calculated.

68
Markie is riding the Tilt-a-Whirl at an amusement
park. He is spinning around at a constant speed
of 4 m/s. Which of the following is true?

1. He never accelerates during the entire ride.
2. His ride car accelerates towards the inside of
   the circular spin.
3. He decelerates as the ride spins around.
4. He will get sick while on the ride.

69
Noggin Knockers (7 points)- p. 27 1a, 1c, 2b,
3b, 3c, 4

• 1 (2 points)- The skater is accelerating by
  changing direction/spinning/going in a circular
  pattern.
• 2 (2 points)- (15 m/s 0 m/s)/10 seconds 1.5
  m/s/s
• 3 (1 point)- Object is decelerating/negatively
  accelerating/slowing down
• 4 (2 points)- (9 m/s 18 m/s)/3 seconds -3
  m/s/s

70
Velocity vs. Acceleration Extension

• Goal- Create the velocity-time graphs below and
  describe how you moved for each one.
• Procedure Help Switch to Velocity-time graph
  and use the F2 and up buttons to stretch the
  graph to the appropriate scale.
• Conclusion (in complete sentences) What was the
  main difference with your motion in the creation
  of the graphs in this experiment compared to the
  ones in the Velocity vs. Acceleration Experiment?

Time (s)
Time (s)
Time (s)
0
V (m/s)
IV
V
VI
71
Motion Practice Test

1. If the distance between that object and the
   reference pt. is changing.
2. Sidewalk- not moving tree-moving
3. To be drawn
4. 100 m/20 s 5 m/s
5. No
6. Speed and direction
7. To be drawn
8. Acceleration
9. Slowing down- running then stopping, approaching
   a red light, etc.

72
Motion Practice Test (Continued)

1. Velocity units m/s, time units seconds
2. Acceleration
3. Speed or velocity
4. Slowing down
5. 1 minute 60 seconds (120 m/s 60 m/s)/60 s
   1 m/s/s
6. To be drawn
7. Man./Ind. variable (x-axis) time Res./Dep/
   variable (y-axis) distance
8. Rise/Run, determine the slope of the line
9. 3 m/s x 5 s 15 meters
10. (0 m/s 20 m/s)/5 s -20 m/s divided by 5 s
    -4 m/s/s

73
Identifying Main Ideas
- Acceleration

• As you read the section What is Acceleration?,
  write the main idea in a graphic organizer like
  the one below. Then write three supporting
  details that further explain the main idea.

Main Idea
In science, acceleration refers to...
Detail
Detail
Detail
Increasing speed
Decreasing speed
Changing direction
74
Links on Acceleration
- Acceleration

• Click the SciLinks button for links on
  acceleration.

75
End of SectionAcceleration
76
Graphic Organizer

Motion
is described relative to a
is measured by
Reference point
Distance Time
in a given direction is called
equals
Speed
Velocity
77
End of SectionGraphic Organizer