tag:techtv.mit.edu,:Array/185576320 2008-10-10 14:24:44 -0400 MIT Department of Physics Technical Services Group Two carts are connected together on an air track with a spring. Under bright lights you can see the coupled oscillation of the carts back and forth, but under black lights you can see that the center of mass moves at a constant velocity. 103 tag:techtv.mit.edu,:Array/185540260 2008-07-08 10:38:56 -0400 MIT Department of Physics Technical Services Group <p>Two large coils of wire ("Helmoholz coils") are connected to 125V DC power, and produce a uniform magnetic field between the coils. A separate coil is suspended with this field. Switching the polarity of the DC current in the inner coil causes it to rotate in opposite directions.</p><p>This principle is used by devices called <a href="http://en.wikipedia.org/wiki/Galvanometer">galvanometers</a> to measure electric current. </p> 47 tag:techtv.mit.edu,:Array/185479840 2008-08-28 11:45:13 -0400 MIT Department of Physics Technical Services Group <p>A string carrying two weights is hung over a low friction bearing mounted pulley. The weights have slightly different masses, causing a uniform acceleration. When the time it takes the weights to move 1 meter is timed, we can calculate the acceleration of the system due to gravity. Because of the low amount of friction in the system, this value is very close to the theoretical value.</p><p>Read more about the <a href="http://en.wikipedia.org/wiki/Atwood_machine">Atwood Machine</a>. </p> 46 tag:techtv.mit.edu,:Array/185401960 2008-06-25 16:28:50 -0400 MIT Department of Physics Technical Services Group A magnet with a very strong magnetic field is held in place on an aluminum disk. The disk is attached to a motor powered by variable AC current. When the disk rotates, the magnet will levitate above it due to <a href="http://en.wikipedia.org/wiki/Eddy_currents">eddy currents</a> generated in the disk. With the disk spinning, these eddy currents form to oppose the magnetic field of the magnet, making it levitate. When the motor is turned off, the magnet falls back to the disk. 48 tag:techtv.mit.edu,:Array/185377560 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/185341620 2009-01-21 14:43:14 -0500 MIT Department of Physics Technical Services Group A light bulb is connected in series with a coil of very fine copper wire and a DC power supply. The voltage is adjusted so that the bulb glows dimly. When the coil is immersed in liquid nitrogen the resistance of the wire decreases causing the current to increase and the bulb to glow brightly. 71 tag:techtv.mit.edu,:Array/185313840 2009-06-03 15:26:02 -0400 MIT Department of Physics Technical Services Group Odd-shaped objects with their centers of mass marked by orange paint are thrown. While the objects appear to follow very wobbly trajectories when viewed under bright lights, under black lights you can see that their centers of mass travel in smooth parabolas. <br><br> Then center of mass is not necessarily in the center of an object, as demonstrated by the last object in the video (a weighted disk). 91 tag:techtv.mit.edu,:Array/185286900 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 tag:techtv.mit.edu,:Array/185243380 2009-08-17 13:48:58 -0400 MIT OpenCourseWare This course provides an introduction to the chemistry of biological, inorganic, and organic molecules. The emphasis is on basic principles of atomic and molecular electronic structure, thermodynamics, acid-base and redox equilibria, chemical kinetics, and catalysis. 2709