3 ms·
a spinning disk 'averages' its mass distribution. Consider a gyroscope spinning fast. so if all of a sudden you try a push its top northward then that instantan
by bawana 9y ago
a spinning disk 'averages' its mass distribution. Consider a gyroscope spinning fast. so if all of a sudden you try a push its top northward then that instantaneous force pushes down on the north edge of the disk and up on the south edge.Those specific parts of the disk acquire momentum. However because the disk is spinning, the part of the disk that was north soon becomes south. and the southern piece that was moving up is now north.now the momenta of the influenced disk segments act to right the gyroscope.
The same effect can occur during the acceleration of a gyroscope in a missile in space. Even tho there is no gravity. The effect of acceleration on the gyroscope is the same, causing it to maintain its orientation in space.
The faster a gyroscope spins, the more quickly it rights itself. and thus appears more stable. as it slows down, the righting effect fails.
- mannykannot 9y agoYes, though I think you can avoid the question of why just "those specific parts of the disk" by considering a dumbbell (two joined, point masses spinning around an axis perpendicular to the center of the rod joining them) rather than a disk or ring, and a continuous torque. If you are pushing northwards on the axis, the maximum rate of change of the instantaneous velocities of the point masses is when they are aligned north-south, and when they are aligned east-west, there is no change in their instantaneous velocity from the applied torque. Integrate this over one revolution, and you get the axis tipping in the east-west plane. A picture would really help, maybe I can find one on the web...
- bawana 9y agoindeed it tips perpendicular to the direction of applied force. and this is what happens in reality. try spinning a bicycle wheel holding its axle on both ends. now try to twist the axle and it curiously wants to move the wheel in a perpendicular direction.