PIRA classification 1L

1L10. Universal Gravitational Constant

1L10.01 falling apple story Quotes from the original accounts of the falling apple and Newton. 1L10.10 Cavendish balance film loop Time lapse of the Cavendish experiment. 1L10.10 Cavendish balance film loop Time lapse of the Cavendish experiment. 1L10.20 Cavendish balance model A model of the Cavendish balance with sliding masses. 1L10.20 Cavendish balance model Model of the Cavendish balance. 1L10.30 Cavendish balance Set up the standard Cavendish balance with a laser beam. 1L10.30 Cavendish balance A platform is used to decouple the Cavendish balance from the building vibrations. 1L10.30 Cavendish balance Quite a bit of discussion about the Klinger KM 1115 gravitational torsion balance. 1L10.30 Cavendish balance Standard Cavendish experiment with lead balls and optical lever detection. 1L10.30 Cavendish balance Mount the Cavendish balance permanently in the classroom and adjust hours before the experiment. 1L10.30 Cavendish balance The commercial device with video over a 1 1/2 hour period. 1L10.33 Cavendish balance - damping A small ball bearing attached to the bottom of the vane dips into a cup containing silicon oil. 1L10.34 Cavendish balance wire replacement Use amorphous metallic ribbon as a wire replacement which gives a higher spring constant and is more durable. 1L10.35 do-it-yourself Cavendish balance A simple Cavendish balance built by sophomore students. 1L10.36 modified torsion balance A very small suspension wire is used allowing the linear accelerations to be measured directly. 1L10.41 resonance Cavendish balance The Cavendish balance is driven into resonance by swinging the external mass. Suitable for corridor demonstration. 1L10.42 servo mechanism Cavendish balance Abstract from the apparatus competition. 1L10.42 servo mechanism Cavendish balance The torsion bar does not appreciably rotate. A simple electronic servomechanism is used to maintain rotational equilibrium as an external mass is introduced. The resulting servo correction voltage is proportional to the torque introduced by gravity. This effect can be observed in tens of seconds. 1L10.43 Cavendish balance compensation Modify the Leybold Cavendish balance with a electromagnetic servosystem of damping that reduces the settling time to a few minutes. 1L10.45 automatic recording Cavendish The reflected laser light from the Cavendish balance falls on a two-element photodiode mounted on a strip chart recorder with appropriate electronics to keep the spot centered on the diode. 1L10.50 gravitational field model

1L20. Orbits

1L20.10 gravitational well - rubber diaphragm 1L20.10 gravitational well On making a rubber diaphragm type potential well. 1L20.12 gravitational well on OH proj Making a Lucite 1/R surface for use on the overhead projector. 1L20.14 elliptic motion A ball rolling in a funnel or cone. 1L20.16 gravity surface Using the Playskool Baby Drum Drop as a gravity surface. 1L20.17 orbits in a wineglass A properly shaped wine glass is used with ball bearings to show radius to orbit period, orbit decay, etc. 1L20.18 orbits in a spherical cavity Derivation of the period of a ball orbiting in a spherical cavity. Strobe photography verifies as a demo. 1L20.30 rotating gravitational well A ball placed in a rotating potential well demonstrates the path of a satellite. Use a variable speed motor to show escape velocity. 1L20.31 escape velocity A Fake. Pour water into a can with a hole in it and then twirl around until "escape velocity" is reached. Show no water remains. 1L20.32 satellites A very complex satellite simulator. 1L20.35 spin-orbit coupling A spinning ball orbits in a watch glass with increasing radii until it escapes. 1L20.36 "Motion of Attracting Bodies" film Meeks film, 6:30 min. Computer animated. Covers Newton's laws, earth's gravity variations, satellite and binary orbits. 1L20.40 conic sections A dissectible cone is cut several ways to give a circle, ellipse, parabola, and hyperbola. 1L20.40 sections of a cone The standard wood cone. 1L20.45 drawing ellipses The two nail and string method for ellipse drawing. 1L20.50 ellipse drawer An aluminum bar with adjustable pegs and a loop of string for drawing the ellipse. 1L20.51 ellipse drawing board The two nail and string method of drawing on paper. 1L20.55 orbit drawing machine Design for orbit drawing machines for use on the overhead projector. A simple one draws elliptical orbits only, an elaborate one draws general Coulomb orbits. 1L20.61 dry ice puck orbits A dry ice puck on a large table is tethered through a hole in the center to a vacuum ping pong ball device under the table that gives an inverse square law force. Construction details p.573. 1L20.62 dry ice puck Kepler's law A dry ice puck has a magnet mounted vertically with a second one below the table which may be inverted to show both attraction and repulsion. 1L20.62 dry ice puck Kepler's law A strong magnet is placed under the air table and a magnetic puck with a light is photographed. 1L20.62 air table Kepler's laws With a strong magnet below the table, take strobe photos of a magnetic puck to demonstrate equal areas. TPT 8(4),244. 1L20.63 dry ice puck Kepler's law Motor at the center of the table with a special pulley arrangement. 1L20.64 areal velocity conservation Analyze a strobe photograph of one cylindrical magnet on dry ice approaching another and deflecting. 1L20.65 fancy air puck Kepler's law The puck has a variable thruster and is of variable mass. A Peaucellier linkage is used to apply central force. 1L20.66 "gravity" with magnetic field Drop a ball near a magnetron magnet and watch it curve around about 150 degrees. 1L20.69 inverse square law motion Pointer to A-62, A-63. Very crude models of planetary motion. 1L20.71 "Planetary Motion and Kepler's Laws" Meeks film, 8:45 min. Computer Animated. Shows orbits of the planets, covers Kepler's second and third laws.