Dynamics Track
Inclined Plane
Momentum

Capacitor
Plate Sep
Plate Sep/Volt
Dielectrics

Circuits
Ohms Law
Series/Parallel

Wave Tank
Freq/Wavelength
Two Pt Interf.

Optical Bench
Refraction
Focal Length

 

 

Dynamics Track

Acceleration on an Incline

A vehicle coasting up an incline will naturally slow down, stop, and reverse direction.   The purpose of this lab is to monitor the position and acceleration of a mass cart as it travels on an incline.   A cart launcher will be used to give the cart a push up the incline.

Equipment:

  • Dynamics track
  • Vernier interface
  • Motion Detector
  • iBook computer
  • Accelerometer
  • Collision Cart
  • Angle Indicator
  • 36” tall ring stand
  • Cart Launcher
Cautions:

This equipment is delicate.   Just about any part of it will be damaged by dropping onto the floor.   Never leave a cart on its wheels unless it is sitting on the track, as it will roll quietly off of the table when you least expect it!   Always set the carts upside-down when they aren’t on the track.   The accelerometer and position sensor are fragile and must be handled gently.










Procedure to set up the inclined plane experiment:

You will most likely find the equipment already set up.   Check each step below to make sure that the setup is correct.   Don’t assume that anything is correct until you verify it yourself!

  1. Set the dynamics track on the lab table with the measurement scale toward you.   Make sure that the track is secure and not going to be bumped by passerbys.
  2. Make sure that the angle indicator is attached to the right end of the track.
  3. Using the ring stand clamp, adjust the angle of the track to 4 degrees.   Be sure to allow the angle indicator time to stop swinging and to make sure that the thread just covers the 4 degree mark!
  4. Mount the cart launcher on the left end of the track.   Slide its nut into the groove in the track and secure it to the track by firmly tightening the mounting screw.

  5. Adjust the cart launcher so that the spring is compressed 4cm in the cocked position.   Do this by:
    1. Place the launcher in the cocked position (the round latching clamp held by the hook)
    2. Loosen the wing nut on the latching clamp
    3. Slide the shaft until its index line is at the 4cm mark
    4. Tighten the latching clamp.
    5. Release the launcher so it won’t go off at the wrong time!
  6. Attach the accelerometer to one end of the mass cart with a dab of “Quake Hold” putty.   The arrow on the accelerometer should point toward the far end of the cart, parallel to the direction of motion of the cart.   Make sure that the side of the sensor opposite the direction of the arrow is firmly aganst the inside of the collision cart.   You don’t want this sensor wiggling around!
  7. Place the cart on the inclined track with the arrow on the accelerometer pointing to the right (uphill).
  8. Make sure that the accelerometer wire is free to move along with the cart without getting caught on anything.  
  9. Open the motion detector 90 ° and place it at the far right (uphill) end of the dynamics track.   Aim the gold sensor disc about one foot above the cart.   The easy way to check this is to put your head one foot above the car and look toward the motion detector.   If you see your face reflected in the gold sensor disc the aim is right!
  10. If it hasn’t been done already, set up the Vernier Labpro interface as follows:
    1. Plug the cable from the acceleration sensor into the “CH 1” socket on the interface.
    2. Plug the cable from the motion detector into the “DIG/SONIC 1” socket on the interface.
    3. Plug the wire from the power supply cube into the interface.
    4. Plug the USB cable into the interface.
    5. Open the iBook computer   If desired, you can hook the iBook to its power supply and line power.
    6. Push the power button near the screen on the iBook.   Wait for the computer to come up to the logon screen.
    7. Plug the USB cable into socket 1 on the left side of the iBook
    8. Double-click on “Student” and enter the password “student”.
    9. Click on the Student tab at the bottom of the screen.
    10. Click on Lyle’s Inclined Plane.
    11. Click on Open…
    12. Click on “Lyle’s Inclined Plane”
    13. Check to see if there is a button near the top of the screen labeled “Collect”.   The presence of this button indicates that the computer can “see” the sensors present and is ready to collect data.

Now you will collect some data!
  1. Cock the cart launcher and let the cart rest on the rubber plunger tip.
  2. Click on the “Zero” button near the top of the screen of the iBook.  
  3. Click on the “Zero all sensors” button.
  4. Have one partner click on the “Collect” button on the iBook.
  5. The other partner waits for the motion detector to start clicking, then pulls the string to trigger the launcher.   For good data, the student pulling the string should step away from the track and make sure that other students do not move about near the experiment.
  6. Wait 6 seconds for the data collection to end.

You should now see your distance and acceleration data on the screen.

  1. Take a look at your graphs.   The distance graph should be a broad, smooth, inverted “U”.   If the distance graph has any “jagged” points, you should adjust your setup (re-aim the motion sensor, eliminate background reflections, etc.) and repeat the collection.   The acceleration graph should show a strong spike at the start and end of the run with a fairly constant negative acceleration between.   A little roughness in the acceleration graph is OK   You may repeat the measurement several times!   Don’t continue until you get a smooth distance curve!
  2. Answer the following questions:

Did the cart acceleration vary much between the end spikes?   What might be the cause of the variation?


What was the car’s acceleration during the run?   Fill in the appropriate space in the table below.   You might want to average several values from the table window to arrive at a better number

Angle

4 degrees

6 degrees

8 degrees

10 degrees

Acceleration


What was the acceleration of the cart when the cart was stationary at the top of its travel (and the distance measurement was a maximum)?

Angle

4 degrees

6 degrees

8 degrees

10 degrees

Acceleration


Did the cart’s velocity direction make any difference in its acceleration?










Change the angle of the track to 6 degrees and repeat the measurement.

Change the angle of the track to 8 degrees and repeat the measurement.

Change the angle of the track to 10 degrees and repeat the measurement.

Discuss the effect of track slope on the acceleration of the cart.


Experiment cleanup:

  1. Click on “Data”
  2. Click on “Clear All Data”
  3. Click on the “Yes” button.   Now the computer is ready for the next lab group.
  4. Click on File
  5. Click on Quit
  6. Click on Don’t Save
  7. Click on the “Student” tab.   It will go back to the bottom of the screen.
  8. Click on Special
  9. Click on Shut Down
  10. Make sure that the experiment setup is left as you found it.   Make sure that the cart cannot roll away!