2) If the car isn’t all the way to the left on the table, then push it over so that it is. The stands up on the right shelf are photo gates and can be moved by dragging their base. They project infrared light in a beam and determine if anything is passing in front of it by detecting infrared light bouncing off of that passing object. The photo gate must be turned on to work (a small button on the left side of the base) and the emitter (the square object on the vertical rod) must be adjusted to the proper height. It is possible for an object to go under the beam and not be detected. There is a tape measure on the table. If you click on the black button you can then move the tape body and make the graduated tape come out. Click again on its button and then the whole tape measure may be moved. Notice that the tape is graduated in cm with every 10 cm marked with a number.
3) Place photo gate 1(PG1) about 20 cm to the right of the nose of the car. Place PG2 more to the right (your choice where) and finally PG3 further to the right. Turn each on and set their emitter as far down as it will go. Use the tape measure to determine the distance from PG1 to PG2 and record. Record the distance from PG1 to PG3. The distance from PG2 to PG3 need not be recorded. Turn on the receiver, the large unit on the left shelf, by clicking on the On / Off button. Set the selector button, on the left of the unit, so that the “Multiple” setting is selected. Note that PG1, 2 and 3 are listed on the screen.
4) With the car in its far left position, click on its start button to the rear of the car. The car will move to the right and stop when it reaches the right of the screen. As it moves past PG1 – 2 and 3, the receiver will record the time the car takes to travel from PG1 to PG2 and from PG1 to PG3. Record these two times. The reason you placed PG1 a few cm to the right of the car is to make sure that the car reaches a constant velocity before any times are taken. These cars almost jump to constant velocity immediately but its best to make sure by giving it a little distance. Calculate the average velocity for the car from PG1 to PG2 and record. Do the same for PG1 to PG3 and record. For help on these values read at the bottom. You may wish to reset PG2 and PG3 to different distances and recalculate the average velocities, they should all be the same. Move to room 2.
5) Again place the car to the far left. Measure the length of the car and record. Place PG1 in the middle of the table, adjust the emitter and turn on the unit. Turn on the receiver and set it to “Single” reading. Here the receiver will start measuring time when the nose of the car passes the center of the photo gate and then record when the car’s tail passes by. Start the car and record the time it takes to pass by PG1. (note that PG1a will always read 0.000 sec.). Calculate the velocity of this car and record. Move to room 3.
6) The velocity of each car has already been determined, in this room, and is listed above the individual car, record their values. Take the tape measure and determine the distance from the nose of the left car to the nose of the right car and record. Calculate the time it will take for each of the cars, when started at the same time, to collide in the middle of the table.(View Data and Hints will help here below) Record the time you calculated. Calculate and record how far the left car will travel in this time and place the marker found on the shelf on this spot. This actually represents where the right car will be also at the end of the run. Push the button on the remote unit to start the two radio controlled cars at the same time. Observe how close you were to the actual spot where the collision takes place. The computer will record how close you were. If you press reset, unlike room 1 and 2, a new set of velocities will be generated and new calculations will be needed.
7) Calculate the requested values asked for on the lab sheet