Photo Journal 

Day 1: 1/13/05

The first and foremost problem that we faced with our project was finding a launching device that could supply a constant force to flip the penny into the air. Since we couldn’t find an existing device, we decided to make one of our own design with the materials we had. So we created one out of 2 wooden boards about a foot in length and a spring launcher. The actual design of the launcher is depicted in the picture below. As can be seen in the photograph, the 2 boards were attached perpendicularly and the spring launcher was mounted on the base board at an angle, aiming towards the edge of the vertical board on top of which the penny would rest. A photogate was connected on either side of the penny launcher, which was created later on during our project and will be discussed shortly.

Day 2: 1/14/05

To complete our penny launcher, we needed to add a triggering device to it that would send signals to the computer to activate the flashes when the penny was flipped into the air. The triggering device that we chose was a photogate, which we developed ourselves by creating the circuit required for a photogate on a breadboard and connecting it to the PT and the LED components at the sides of the penny launcher, secured by a piece of metal at each side of the launcher.

Day 3: 1/19/05

After our penny launcher was finished, we set up the computer program, Multiplexer, that would control the delay and interval times of our 8 flashes. We also set up the input and output boxes that would connect to the computer and serve as relay centers for messages coming into and out of the computer. In addition, we hooked up the photogate circuit to the input box, to receive messages from the photogate when activated, and to the output box, from which the circuit received its power supply. After all of this was set up, we tested all of the equipment by launching the penny using the penny launcher and watching whether the photogate activated and sent a message to the computer.

Day 4: 1/25/05

Today we set up our 8 flashes, which we put in a row on top of an adjustable height table, facing the side of the penny launcher. We connected the flashes to the output box, from which they receive the signal to discharge. We then tested to see if all the flashes went off at their set delay and interval times. This test was successful, so we then proceeded to experimenting with the delay and interval times on the computer to find the right ones for our penny trajectory. However, turning the room lights off to do this experimentation activated the photogate, which presented a problem to us because our pictures of the penny had to be taken in the dark. After spending quite a lot of time trying to figure out what the problem was, we determined that the problem was one of the resistors in our photogate circuit. We had mistakenly put a higher resistance resistor in our photogate circuit than what was called for in the instructions.

Day 5: 1/27/05

Most of the day was spent trying to finish setting up the equipment we needed for our experiment. This included setting up the camera and positioning it such as to get the best view of the top of the penny trajectory. We took a few pictures of the penny trajectory without using the photogate and computer controlled flashes so that we could adjust the position of the camera so as to capture the top of the trajectory in our pictures. One of these pictures showing the penny trajectory is depicted below. We also had to make 2 marks on our penny launcher to indicate the level we needed to pull the spring launcher down to in order to supply 2 different, constant forces. Once all the equipment was in place, we were ready to take pictures.

Day 6: 2/1/05

Today we took initial pictures of the flipping penny launched with a force corresponding to the 1^st mark on the spring launcher (let’s call this force 1). After taking about 5 pictures of the flipping penny, we reviewed the pictures on the computer and decided that we needed to increase the aperture on our camera because the penny looked too dark in our pictures (see picture below). We adjusted the aperture from f/8 to f/5 and then took more pictures. After reviewing the new set of pictures, we decided to decrease the aperture slightly to f/6.3. We also thought that painting one side of the penny pink with nail polish would help us distinguish which side of the penny faced up at the top of the trajectory more easily. After having made these changes, we were ready to take more pictures. We also started creating our website today to display the results of our project.

Day 7: 2/2/05

We started our work today by taking pictures of the penny launched tails up with a force 1. We took about 5 good pictures of the flipping penny under these initial conditions. Next, we took about 5 more pictures of the penny launched heads up with the same force (force 1). We analyzed these pictures on the computer, using Photoshop, and decided that we were happy with the results. So, we proceeded with taking pictures of the penny launched with force 2, first with the heads side up and then with the tails side up. We took about 5 pictures for each initial condition. After having finished taking all of our data (i.e. pictures), we took a few photos of our experimental setup.

Day 8: 2/3/05

Most of the day was spent on adding content to and modifying our website.

Day 9: 2/4/05

Today we spent all of our time analyzing our photos. We reviewed each photo carefully in order to determine which side of the penny was up at the top of the penny’s trajectory in each photograph. We recorded all of our results in our lab notebook and started to analyze the recorded data with statistical methods.