Testing Newton's Third Law predictions

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

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.

Go to the folder

        My Computer -> 
           Student Shares on svphy01 -> 
              University Physics Students -> 
                 Team Physics 311 -> 
                   Lab Pro

and copy the file newton_3mwr to the Desktop folder.

Run the Logger Pro program by choosing Start -> All Programs -> Vernier Software -> Logger Pro 3.4.6 Go to the File item, choose "Open", and open the Desktop -> newton 3mwr file. This will set up the screen and sensors for today's experiment.
You'll see a couple of windows pop up -- just press "OK" to each.
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.
Calibrate the sensors by providing a known force. Choose Experiment -> Calibrate to bring up the calibration menu. Be sure the slide switch is in 50 N position. Hold sensor vertically and enter zero for the force. Now hang a total of 550 grams from the sensor's hook (be sure to include the mass of the hanger) and enter the weight in Newtons: W = (mass in kg)*(g). Finally, press "Done" to finish the calibration.
(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.)
Repeat the calibration procedure for the other sensor.
Replace the hooks on the force sensor with rubber bumpers.

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

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.
Set up experiments to check the results that you predicted for the two situations. Enter your observations into the appropriate column in the table.
Replace the rubber bumpers on the sensors with hooks. You will need to return your rubber bumpers to the instructor in order to receive full credit.

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.

Don't put away the equipment! We'll use it again in a short time to measure forces of friction.