tag:techtv.mit.edu,:Array/185236860 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/185210280 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/185177900 2008-09-02 10:20:19 -0400 MIT Department of Physics Technical Services Group <p>A stuffed monkey is suspended from a rod at one end of a lecture hall by an electromagnet. A golf ball gun aimed directly at the monkey cuts power to the electromagnet when fired. Thus, the monkey begins falling at the same instant the gun fires the golf ball. The projectile and target meet in mid air.</p><p>Intuitively one might think that the ball will go over the monkey's head due to its fast speed. However, gravity accelerates all objects downward at the same rate, meaning the monkey and the ball will meet at exactly the same point. If the ball was shot even faster, it would still hit the monkey, but higher above the ground. </p><p>No animals were harmed in this demo. </p> 77 tag:techtv.mit.edu,:Array/185149980 2008-09-02 15:54:18 -0400 MIT Department of Physics Technical Services Group A ball is dropped in front of a meter stick and lit by a strobe light. A long exposure photograph captures the position of the ball at each evenly spaced flash of light. The acceleration of the ball can then be measured from the photo. <br><br> Note that the frame rate of the video capture (30fps) is quite close to the strobe rate (15Hz). This is why the strobe flashes in the slow motion video don't appear to be exactly evenly timed. <br><br> See the <a href="http://www.flickr.com/photos/physicsdemos/3174207211">final image</a> on Flickr. 42 tag:techtv.mit.edu,:Array/185127520 2008-09-02 15:08:22 -0400 MIT Department of Physics Technical Services Group A pair of spinning wheels 1.5 meters apart is placed in the path of a bullet. A bullet is fired with the wheels stationary for reference position, and fired again with the wheels spinning at a known speed. The second wheel will rotate more than the first as the bullet crosses the gap between them. When the angles between the reference holes and the second holes are compared, the speed of the bullet can be determined. <br><br> The balloon is used to show when the bullet has passed through both disks. <br><br> This video was shot with a Phantom v7.1 high speed video camera (donated by Vision Research Inc.) at approximately 7000 frames per second. The frame data can be seen at the bottom of the screen. <br><br> Special thanks to Dr. Jim Bales, MIT Edgerton Center. 22 tag:techtv.mit.edu,:Array/185091980 2008-10-21 11:04:51 -0400 MIT Department of Physics Technical Services Group A CO2 fire extinguisher is mounted on the back of a tricycle. When the CO2 is released, the tricycle is propelled forward. Watch Professor Lewin perform this demonstration on the Martha Stewart Show: <a href="http://www.marthastewart.com/show/the-martha-stewart-show/teacher-appreciation-day?lnc=4ef2dc5bfca40110VgnVCM1000003d370a0aRCRD&amp;rsc=showarchive_tv_show-archive">http://www.marthastewart.com/show/the-martha-stewart-show/teacher-appreciation-day?lnc=4ef2dc5bfca40110VgnVCM1000003d370a0aRCRD&amp;rsc=showarchive_tv_show-archive </a> 53 tag:techtv.mit.edu,:Array/185060680 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/185032820 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/184973820 2009-08-19 11:28:08 -0400 MIT Department of Physics Technical Services Group Two demonstrators sit at either end of a rotating platform and toss a ball back and forth. When viewed from the rest frame (when the camera is mounted to the ground), the ball follow a straight line but doesn't reach its target because during the ball's flight the target rotates away. When viewed from the rotating frame (when the camera is mounted to the rotating platform), the ball appears to experience a force that pulls it away from the target. <br><br> This curved trajectory in the rotating frame is known as the "Coriolis Effect", sometimes called the "Coriolis Force", though it disappears in the rest frame. The Coriolis Effect can be seen in many situations where rotating frames are encountered, especially meteorology and astronomy. Atmospheric systems, for example, often follow circular patterns due to the Coriolis effect. Airplanes and missiles appear to follow curved trajectories when seen by observers on Earth as the planet rotates underneath. 181