Lab 3: Motion in One Dimension.
Introduction and Objectives
This is the first lab exercise that will use simulations and will explore motion in one dimension.
WARNING: Simulations will feel very much like you are playing a video game. The difference, however, is that you will be required to answer questions about what is happening. Do not yield to the temptation to only go through the motions, and submit something, anything. If you don’t actively participate it will be readily apparent in your lab report.
Here is the procedure for this lab exercise.
To complete this exercise you will need to access the Moving Man simulation at PhET.
Here’s the URL for the simulation: http://phet.colorado.edu/sims/moving-man/moving-man_en.jnlp
Here is a link to an executable JAR file that can be downloaded and run directly on your computer: moving-man_en.jar
Lab 3 Report
When you have completed the lab exercise given in the sections above:
Write your paragraphs according to the standard Lab Report Format.
Scan your worksheets into either a PDF or MS-Word (DOC or DOCX format) document.
Attach the documents to the box below.
Lab 3 – Motion in One Dimension
The study of motion, known as kinematics, is the first step that we must take in learning physics. This lab will explore the relationship between position, displacement, velocity and acceleration.
The position is defined as the location of the object in space. In one dimension, the position is generally given the symbol x where positive values of x (x > 0) means that the object is located in the +x direction relative to a well-defined origin. Similarly, negative values of x mean that the object is located in the -x direction. The displacement ?x is defined as the difference between a final position, x, and and initial position x0 by the equation –
The velocity is defined as the rate at which the displacement is changing. In mathematical terms
where is the difference in time between the initial and final positions.
The acceleration is defined as the rate at which the velocity is changing and is defined as – –
where and are the initial velocities and times, respectively.
When the student has completed this lab, they should be able to:
? Have an intuitive sense of how position changes result in velocities
? Have an intuitive sense of how velocity changes result in accelerations
? Have developed the abilities to obtain useful physical information from simulations.
? Have developed the ability to run simulations on a computer.
To complete this lab you will need to access the Moving Man simulation at
Before we start performing detailed simulations, we will begin by familiarizing ourselves with the Moving Man simulation.
(a) Go to the Moving Man web page and start the simulation. You can either download the application, or you can download the applet from Blackboard and run it on your computer.
(b) For this part of the lab we will use the Introduction Tab on the applet as shown below.
ACTIVITY: (a) For the first activity we will explore the basic controls. Ensure that the Record radio button at the bottom of the application is checked as shown in the following figure.
(b) Press the Play button to start recording.
(c) Use the blue Position Slider to begin moving the man to the left and right. After having moved him several times, type a number in the box to move the man to a specific location.
(d) Press the pause button to stop recording. Click on the Playback radiobutton and the Play button to review your motions.
(e) Repeat steps (a) through (d) using first the velocity slider and
then the acceleration slider.
(f) When you have completed the above steps answer the following questions. You may need to go back and perform them a second time to answer some of the questions.
QUESTION: How does the Moving Man react when you adjust the blue Position Slider.
QUESTION: How does the velocity slider react when you adjust the blue position slider?
QUESTION: How does the green acceleration slider react when you adjusted the blue position slider?
QUESTION: When you adjusted the red velocity slider, how did the blue Position slider and green Acceleration sliders react?
2) Motion with Constant Velocity
We are now going to explore how the Moving Man behaves when you move him with constant velocity.
Click on the Charts Tab of the applet. You will see the following image:
If you click on the minus signs at the right-hand margin of each chart you can hide the chart. Begin by closing the Acceleration chart because the acceleration for this part of the lab will be equal to zero.
ACTIVITY: (a) Set up the simulation to record the motion using the controls at the bottom of the window.
(b) Type a relatively low velocity in the velocity box. Record the motion. Adjust your motion so that the time it takes the man to move to the wall is reasonable. (To fast and he hits the wall almost instantaneously, too slow and his motion is not apparent.)
(c) Use playback to record your run.
(c) Answer the questions when you have run the simulation several times with different velocities, both positive and negative.
QUESTION: Describe his position as a function of time when the velocity is positive?
QUESTION: Describe his position as a function of time when the velocity was negative.
QUESTION: How far could the man move in each case? What happened when the man reached the wall?
ACTIVITY: (a) Assume that the man starts in the middle at a position of x = 0. If you want him to move 6.0 meters in 1.5 seconds, what is his velocity?
(b) Insert the result of the calculation in part (a) into velocity control of the Moving Man simulation. Run the simulation until the man reaches one of the barriers.
(c) Use the cursor to determine how long it took the man to move 6.0 meters. Record this number.
t(6.0 meters) = _____________________
(d) Use the cursor to determine how long it took the man to move 9.0 meters. Record this number.
t(9.0 meters) = _____________________
(e) Now use the Playback mode to answer the questions below.
QUESTION: What is the shape of the position curve?
QUESTION: Did the time that the simulation needed to move man by 6.0 meters match the number you calculated? If not, why not?
QUESTION: Use the velocity you entered in the simulation to calculate the time needed to move 9.0 meters. How does your theoretical prediction compare with the result from the simulation?
3) Motion with Constant Acceleration
Activity: (a) Using the diagrams below, predict what the velocity and position curves will look like with a constant acceleration. (These do not have to be drawn precisely to scale.)
(b) Set the position of the Moving Man to the left-most position which will be x0 = -10 m.
(c) Set the initial velocity equal to zero.
(d) Set the acceleration to a small positive value.
(e) Use the following equation to determine how long it will take the moving man to move from his initial position to the right-most side of the simulation. (x = +10 m) with the acceleration that you chose. Adjust your acceleration as needed to get the man to move to the right for 10 to 20 seconds. v ( – )
(f) Calculate the maximum velocity that the man will achieve just before he runs into the barrier. v ( – )
(g) Run the simulation until the man gets to right-hand barrier. Make sure that you record the motion for later analysis.
(h) When you are finished, use the cursors and Playback mode to answer the questions below.
QUESTION: Did your predicted time (Step e) and maximum velocity (Step f) agree with the values of the simulation. If not, why not?
QUESTION: Did your prediction for the form of the velocity curve match the results of the simulation? If not, why not?
QUESTION: Did your prediction for the position curve match the results of the simulation? If not, why not?
QUESTION: Describe the acceleration of the man when he hit the barrier. What does this mean physically? Open up the Acceleration chart. Did your prediction agree with what was observed. If not, why not?
4) Arbitrary Motions
ACTIVITY: Use the Position slider to move the man in an arbitrary manner. Record the motion. Use the operating system’s Screen Clip tool to capture the charts for your motion. The result of running this part of the lab will look like the following:
QUESTION: Sketch and describe the three kinematic parameters: position, velocity, acceleration. Describe the link between the accelerations, velocities, and positions?
QUESTION: When is the velocity positive? How is the position changing when the velocity is positive?
QUESTION: When is the velocity negative? How is the position changing when the velocity is negative?
QUESTION When is the acceleration positive? How is the velocity changing? When is the acceleration negative? How is the velocity changing?