tag:techtv.mit.edu,:Array/218037000 2008-08-27 16:48:12 -0400 MIT Department of Physics Technical Services Group <p>A bicycle wheel is suspended from one of end of its axie by a rope, and spun up by hand. The wheel's axle is then placed horizontally and the free end of the axle processes about the supported end. </p><p>The gyroscope seems to defy gravity because the torque created by the spinning wheel counteracts the torque due to gravity. Read more about gyroscopes <a href="http://en.wikipedia.org/wiki/Gyroscope">here</a>. Gyroscopes have been used through history for varied uses such as stabilizing spacecraft or for guidance systems on ships and missiles.</p> 89 tag:techtv.mit.edu,:Array/218016220 2008-08-28 14:21:12 -0400 MIT Department of Physics Technical Services Group <p>A wooden ball is attached to the rim of a spinning wheel. The ball is held in place by a string. When the spring is cut, the ball flies in a straight tangent to the wheel.</p><p>In the camera's frame of reference, the ball constantly accelerates around in a circle due to the centripetal force pulling it inwards. When the string is cut, the acceleration stops, and the ball flies away in a straight tangential line. When the string is cut in the rotating frame of reference, a ficticious force (centrifugal force) accelerates the ball. </p> 79 tag:techtv.mit.edu,:Array/217997320 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