Spinning Bicycle Wheel Stays Upright.
• A+30+60
A coffee cup is tied to the middle of a pencil by a strong string. The string is drawn up along a bar by pulling the pencil away at about a 45 degree angle relative to the horizontal. When the pencil is released conservation of angular momentum leads to the pencil rapidly wrapping around the bar which generates sufficent friction to arrest the coffee cup before it hits the ground.
Related Demos
A+30+65
Bike with one foot long trail A+30+70
Hoop thrown forward rolls backwards A+30+0
Minor's apparatus: Movable discs rotated by falling weight. A+30+5
Maxwell's wheel: Flywheel with axle, supported on strings or stand. A+30+10
Rotational inertia device: Sliding weights on rotating rod. A+30+15
Rotating chair with dumbbells or weighted bicycle wheel. A+30+20
Maxwell's top, has adjustable center of gravity. A+30+25
Large conical aluminum top. A+30+30
Gyroscopes; various. A+30+35
Sire's Polytrope. A+30+40
Film: "Conservation laws in zero G", sound, 14 min.. A+30+45
Large gyroscope in a suitcase. A+30+50
Rotating Platform for Outreach A+30+55
Falling coffee cup is arrested by friction