Is It Accelerating?

 

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For this lab, you will use LoggerPro to analyze videos of motion and determine (a) whether or not the object is accelerating, and (b) if it is accelerating, the value of its acceleration.

 

1.     Learning how to curve fit

a.    Open up Applications/Custom/Logger Pro 3

b.   File/Open/Tutorials/09 Curve Fitting

c.    Follow the instructions on pages 1-3 to practice curve fitting.

2.     Getting ready

a.    Download the clips from Moodle. (you & your partner will be assigned a couple of videos to analyze)

                                              i.     In your Physics class folder, make a new folder and name it ÒIs It AcceleratingÓ

                                             ii.     In Moodle, open up the ÒIs It Accelerating?Ó folder.

                                           iii.     Right-click on each file, and choose ÒSave Link As . . .Ó

                                           iv.     Save each movie & the MSWord document into this folder. You'll record your data in the table in the MSWord folder.

b.   In Logger Pro, open up the file ÒVideo Analysis Template.cmbl.Ó

3.     Getting the Data

a.    In Logger Pro, choose Insert/Movie . . .

b.   Select the appropriate movie.  It will appear in a new window within Logger pro.

c.    In the lower right-hand corner of the video window, click on the button with the red dots  to enable video analysis.  A vertical toolbar will pop up to the right of the video window.

d.   Establish your scale by clicking on the ruler  in the vertical toolbar.  Next, select an object of known size that is in the same plane as the motion and click/drag the green line carefully across the object.  Enter the real-life measurement of the object, choosing the correct units (please use metric!).

e.    Click on the point button  on the vertical toolbar.  Advance the clip to just where the motion begins.

f.     Click on a selected part of the object.  As you click, a red dot will appear where you clicked, and the clip will be advanced one frame.  Continue clicking on the same part of the object frame-by-frame until the motion is complete

g.   When youÕve finished putting in these points, double-click on the graph (in a blank space) to change the axes so that the velocity & acceleration are shown as well as the position. 

4.     Fit a best-fit straight line to the velocity.  Record the slope of this line.

5.     Find & record the average value of the acceleration.

 

 

 

 

 

Clip to analyze

What is the slope of the velocity graph?

What is the average acceleration?

% difference between (slope of velocity graph) & (average acceleration)*

How large is the largest acceleration in this clip?

How many gÕs? (One g = -9.81 m/s2)

Hall Bowling X

 

 

 

 

 

Office Bowling X

 

 

 

 

 

Galileo Drop Y

 

 

 

 

 

Punkin

 

 

 

 

 

Elevator Barbie Y

 

 

 

 

 

Foucault X

 

 

 

 

 

Air Resistance Y

 

 

 

 

 

Offset X

 

 

 

 

 

Second collision (note: these clips are replayed at 1/20th actual speed; calculate accordingly!

Neck X

 

 

 

 

 

Heart X

 

 

 

 

 

Skull top X

 

 

 

 

 

Skull center X

 

 

 

 

 

 

 

 

Where did you measure the largest acceleration?

 

 

 

Given a position-time graph of an objectÕs motion, how can you determine if it is accelerating?

 

Given a velocity-time graph of an objectÕs motion, how can you determine if it is accelerating?

 

Describe how you determined the acceleration of an object from its velocity-time graph.