Position and Time Graphs

Position - Time Graphs

Lesson Objective

At the end of this lesson, you should be able to

- Make and Interpret Position - Time Graphs

This graph shows an object moving.

The vertical axis shows position. Is the position changing over time? Yes, it is. So this shows a moving object. This line is straight so the rate of change is constant. Every second the object moves the same amount

This graph shows an object that is not moving.

The vertical axis shows position. Is the position changing over time? No, the object is in the same position. If there is no change in position, the object is not moving.

This graph shows one fast object and one slow object.

The vertical axis shows position. Both lines show a change in position. The red line shows a larger change in position in a shorter period of time. The Green line takes more time to cover a shorter distance.

The red line shows a faster rate of motion than the green line.

Any changes in an object's position over time can be graphed with position on the y-axis and time on the x-axis.

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​Position vs time graph

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Both of these objects are stopped.

Since the vertical axis shows position, these flat lines show the positions are not changing, they are both stopped. The red line shows an object stopped a greater distance from the reference point than the green line.

When reading graphs you have to look at the values on both the vertical (y) axis and the horizontal (x) axis.

You cannot just look at the line or lines. Now try to answer a question about a motion graph.

Multiple Choice

Which graph shows the faster object?

​Sometimes, we use distance to talk about motion. We are talking about the distance away from a certain point. (usually zero meters)

Multiple Choice

Describe the motion of graph A

• At rest (not moving)

• Uniform motion (velocity is staying the same.)

• non-uniform motion

  (velocity is changing)

Multiple Choice

Describe the motion of graph B

• at rest (not moving)

• uniform motion

  (velocity is staying the same.)

• non-uniform motion

  (velocity is changing)

Multiple Choice

Describe the motion of graph C

• At rest (not moving)

• uniform motion (velocity is staying the same)

• non-uniform motion

  (velocity is changing)

Multiple Choice

Describe the motion of graph D

• at rest

  (It isn't moving.)

• uniform motion

  (Velocity is staying the same.)

• non-uniform motion

  (Velocity is changing.)

Multiple Choice

True or False: B is faster than D

• TRUE

• FALSE

Multiple Choice

True or False: D is faster than A

• TRUE

• FALSE

Multiple Select

Which object(s) are accelerating?

(Accelerating means that the velocity is changing.)

• A

• B

• C

• D

• E

Multiple Select

Which object(s) are NOT moving? There may be more than 1 answer!

• A

• B

• C

• D

• E

Multiple Choice

Which object is moving fastest?

• A

• B

• C

• D

• E

Multiple Choice

Which object is traveling slowest?

• A

• B

• C

• D

• E

Multiple Choice

The graphs show 4 cyclists on an afternoon ride. Which cyclist stops for a water break during their ride?

• A

• B

• C

• D

The slope of a position vs time graph for an object experiencing constant motion is linear (a straight line).

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​Position vs time graph

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Speed is the rate that a certain distance is covered over time.

​

Speed is scalar.​ It tells us only the magnitude of how fast an object is moving.

​

The SI unit for speed is meters per second (m/s)​

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Speed

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The slope of a linear graph can be calculated with rise over run.

Slope of a d-t graph

In position ​(d) vs time (t) graphs, the slope of the line represents the velocity of the object!

Describing the Motion

Object is moving in a positive direction ​away from the origin with a constant positive velocity.

​Object is at rest at a positive position away from the origin.

​Object is moving in a negative direction towards the origin with a constant negative velocity.

Describe the motion.

Multiple Choice

Which time segment shows the object at rest?

• 10-15 seconds

• 30 seconds

• 15-40 seconds

• 55 seconds

Multiple Select

Which cyclist(s) have a displacement of 0m?

• A

• B

• C

• D

Multiple Choice

Which cyclist(s) have traveled the farthest total distance?

• A

• B

• C

• D

Multiple Choice

What letter is located at (x, y) = (8, 5)?

• A

• B

• C

• D

Multiple Choice

Which runner won the race?

• A

• B

• C

Multiple Choice

What is going on with the object here?

• Speeding Up

• Slowing Down

Multiple Choice

Who's faster?

• Barkus

• Arctica

Multiple Choice

What is the speed of a car that travels 400 m in 20 minutes?

• 20 mi/hr

• 20 m/min

• 800 m/min

• 200 mi/hr

Multiple Choice

Soccer ball A goes 15 feet in 3 seconds, and ball B goes 12 feet in 2 seconds. Which ball moved the fastest?

• Soccer ball A

• Soccer ball B

• Their speeds are equal.

Multiple Choice

What is happening at D?

• Stationary

• Accelerating

• Fast steady speed; moving away from the starting position

• Slower steady speed; moving away from the starting position

Multiple Choice

What is happening at E?

• Stationary

• Accelerating

• Fast steady speed; moving away from the starting position

• Steady speed; returning to start position

Multiple Choice

Why did Arctica lose the race?

• She stopped

• She ran too slow

Multiple Choice

Look at the graph above. It shows how three runners ran a 100-meter race. Which runner won the race?

• Albert

• Bob

• Charlie

Multiple Choice

Which runner stopped for a rest?

• Albert

• Bob

• Charlie

Multiple Choice

The slope of a line of an object's position-time graph is the ______________ of the object

• Displacement

• Time

• Acceleration

• Velocity

Multiple Choice

Which of the following trains has a positive velocity

• Train 1

• Train 2

Multiple Choice

Match the description to the graph:

"The speed of the car is decreasing."

Multiple Choice

• 4 m/s

• 3 m/s

• 0 m/s

• -5 m/s

Poll

How well do you understand POSITION VS TIME GRAPHS now?

• I understand it all!

• I understand most of it.

• Not really.

• I don't think I'll ever understand it