tag:techtv.mit.edu,:Array/219002840 2008-11-26 14:05:36 -0500 msrp2008 "It's not just about the books. It's not just about the research. You've got to try to do what you can to give back." --Brandon Johnson, Senior, University of Maryland, Baltimore County 94 tag:techtv.mit.edu,:Array/218981740 2008-12-01 10:16:11 -0500 msrp2008 "You realize that you're not in competition with anyone else here. You're in competition with yourself." --Bianca Jones, Senior, St. John's University 113 tag:techtv.mit.edu,:Array/218959900 2008-12-15 15:40:12 -0500 MIT Department of Physics Technical Services Group Two identical metal balls are dropped from the same height using an electromagnetic release. One ball is dropped freely, while the other hangs from a string, acting as a simple pendulum. Using two photogates, we see that the vertical velocity of the dropped ball is identical to the horizontal velocity of the pendulum, measured at the same height. Potential energy has been converted to kinetic energy equally in both cases. 72 tag:techtv.mit.edu,:Array/218938780 2009-01-06 13:23:42 -0500 MIT Department of Physics Technical Services Group A plexiglass rod rubbed with fur picks up a positive electric charge, while a rubber rod rubbed with fur picks up a negative electric charge. When either rod is brought in contact with hanging tinsel, the tinsel becomes charged and flares out. The other rod, however, will now attract the tinsel. Touching the tinsel with your hand discharges it. <br> <br> These electrostatic forces can also be seen with a conducting balloon. Touching a charged rod to the balloon transfers charge, causing the balloon to be repelled away from the rod. <br> <br> The ancient Greeks noticed this phenomenon when rubbing pieces of amber (which pick up a negative electric charge, like our rubber rod). The word "electricity" is based on the Greek name for amber: "elektron." 123 tag:techtv.mit.edu,:Array/218919160 2009-01-14 12:37:06 -0500 MIT Department of Physics Technical Services Group A <a href="http://en.wikipedia.org/wiki/Wimshurst_machine">Wimshurst electrostatic generator</a>, working on the principle of induction, generates high voltage differences and sparks between two movable electrodes. By increasing the distance between the electrodes, higher potential differences can be built up. <br><br> <a href="http://en.wikipedia.org/wiki/Electrostatic_induction">Electrostatic induction</a> refers to the principle that charges in an object (especially a conductor) redistribute themselves in the presence of nearby charges. Opposite charges are attracted to each other, while similar charges are repelled. <br><br> Larger charges can be stored by connecting the knobs to Leyden jars which are component parts of the machine. 151 tag:techtv.mit.edu,:Array/218900080 2009-01-22 15:13:38 -0500 MIT Department of Physics Technical Services Group <a href="http://en.wikipedia.org/wiki/Leyden_jar">Leyden Jars</a>, an early style of capacitor, can be connected to the two electrodes of the Wimshurst Machine. They will store charge as it is generated, giving a much stronger spark across the gap. <br><br> Next we have a three-piece dissectible Leyden Jar consisting of two metal cups separated by a glass cup. When charged with the Wimshurst machine, we see by touching it with the shorting rod that it holds a large amount of charge. However, when disassembled, the metal cups can be brought into contact with each other and no spark will be generated. When the jar is reassembled it can then be discharged. This demonstrates that, in this situation, the charge actually resides on the surface of the glass (a <a href="http://en.wikipedia.org/wiki/Dielectric">dielectric</a>), not on the metal. 175 tag:techtv.mit.edu,:Array/218881120 2009-05-27 11:18:37 -0400 MIT Department of Physics Technical Services Group Rubbing the rim of a wine glass with a wet finger will cause it to resonate at its resonant frequency. The glass is placed in front of a speaker playing a sine wave, created by the function generator, of this same frequency. When the amplitude is turned up, we can see by shining a strobe light at the glass that this resonant frequency causes it to oscillate. When the glass becomes too stressed, it will shatter, which we see very clearly on high speed video. <br><br> A few things to note: The scrolling effect seen in the strobe light footage is caused by interference between the strobe light frequency and the video camera frame rate. Also, the real oscillations of the glass are much faster than they appear in the strobe footage. Setting the frequency of the strobe light can make them appear much slower so that we can see the oscillations in real time without the help of high speed video. <br><br> We would like to thank Dr. Jim Bales of the MIT Edgerton Center for helping us with the high speed video recording, and for the use of the equipment. The high speed camera used here is a Phantom v7.1, donated by the manufacturer Vision Research, Inc. 154 tag:techtv.mit.edu,:Array/218862220 2009-06-10 14:04:53 -0400 MIT Department of Physics Technical Services Group Two pucks of the same mass are slid at each other on an air table, and their resulting collisions demonstrate conservation of momentum. Notice on the first collision, for example, that when a moving puck hits a stationary puck dead-on, that the second puck leaves with the same velocity as the first, and the first puck stops moving completely. 80 tag:techtv.mit.edu,:Array/218843320 2009-06-11 14:02:02 -0400 MIT Department of Physics Technical Services Group An air puck is attached to a string that passes through the center of an air table. A weight is attached to the end of the string. The ball is set into rotation in a horizontal circle. When the weight is released, creating a constant force inwards, the radius of the path is shortened and the puck speeds up. A similar effect is seen when the string wraps around a center rod like a tether ball. This creates an increasing force, which causes the puck to inspiral more quickly. 181 tag:techtv.mit.edu,:Array/218824420 2009-06-18 13:08:48 -0400 MIT Department of Physics Technical Services Group A cart moving at constant velocity shoots a ball straight upwards. Since the ball has the same translational velocity as the cart, it is caught when it comes back down. 68