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Last Modified: 2:01pm 10 Aug 11

Testing Newton's Third Law predictions

    First, we need to arrange the sensors and computer to read them.

  1. Get a computer, LabPro, two force sensors with adaptors, and two massive bars. Connect the LabPro to the computer. Use the adaptors at the ends of the force probe cables, and connect the force probes to CH1 and CH2 of the LabPro. The truck should be the sensor connected to CH1, and the car is the sensor connected to CH2. Be sure the slide switch on the force sensors is at 50N. [Note: you do NOT need to use carts and a track for this experiment.]
  2. Go to My Computer -> Student Shares on svphy01 -> University Physics Students -> Team Physics 311 -> Lab Pro, and copy the file F200 Newton's Third Law to the "My Documents" folder.
  3. Run the Logger Pro program by choosing Start -> Programs -> Vernier Software -> Logger Pro 3.3. Go to the File item, choose "Open", and open the My Documents -> F200 Newton's Third Law file. This will set up the screen and sensors for today's experiment.
  4. Zero the sensors: place the sensors on the table and zero both sensors (CNTRL-0). Check the zero by collecting data with the sensors horizontal and not touching.
  5. Calibrate the sensors by providing a known force: Be sure the slide switch is in 50 N position. Hold sensor vertically and enter zero for the force. Now hang about 500 grams (be sure to include the mass of the hanger) and enter the weight in Newtons: W = (mass in kg)*(g).
    (Beware the Tare: There is a "tare" button on the side of the force sensor. Be very careful not to accidentally press it. If you do, you will need to re-zero the sensors, but will not need to recalibrate.)
  6. Replace the hooks on the force sensor with rubber bumpers.

    Okay, now we're finally ready to test your predictions.

  7. Push on each bumper with your hand while collecting data to see how data are collected. If the truck is on the left, pushing to the left on its bumper should give a negative force. A push to the right on the car bumper should give a positive force.
  8. Set up experiments to check the results that you predicted in parts (a) to (d). Enter your observations into the appropriate column in the table.
  9. To check parts (e) and (f) of Newton's Third Law during collisions, you must make a couple of changes to the program. Click on the clock icon (or on menu, Experiment: Data Collection) and a window will open. In the window make the length of the experiment 1 s, and collect 1000 samples per second. Then click the Triggering tab and check Enable Triggering. Check parts (e) and (f) of your predictions. Enter your observations into the appropriate column in the table.

This experiment is designed to help you learn something about Newton's Third Law. Write a clear statement of Newton's Third Law based on what you measured.

Sorry, we could not find this page | RIT CIS - Center for Imaging Science

Sorry, we could not find this page

We apologize, but the page you were looking for is not available. Most of our material is available from the menus above.

Last Modified: 2:01pm 10 Aug 11


Adapted from Prof. Michael Richmond.