Question

Question #0e556

Answer 1

This is a nice question!

The gyroscope is a device that uses the conservation of angular momentum `L` to maintain the axis of rotation fixed in space.

Let say that you have a spinning top; when it spins observe the axis of rotation; if the toy is well made and the spin well done you'll see the toy spin with the axis perfectly vertical....obviously after a while the rotation changes and the toy starts to wobble and the axis of rotation to oscillate.

Now think at the same toy but "helped" in its spinning by enclosing its axis in a frame with very low friction as in the figure below:

The horizontal frame is free to rotate around points `P`.
What happens is equivalent to conservation of linear momentum `vecp` when you do not have external forces acting on your system.

If you have two skaters on ice that collides you have that the momentum (mass times velocity) before and after the collision are the same.

For the blue flywheel in your gyroscope the angular momentum `L` (the rotational equivalent of momentum given as: `vecL=vecRxxvecp`) is:

1) lying along its axis of rotation (the angular momentum of a symmetric body rotating about its axis of symmetry always lies along this axis);

2) it is conserved (in magnitude and DIRECTION!!!!!) if there are no external torques applied on it.
If the contact points of the flywheel are well made and oiled the frictional torque is negligible.

The good thing is that now the angular velocity remains constant and the orientation of your flywheel remains fixed in space!!!!

You can now take the base of your gyroscope and carry it around and no matter how you carry it, turning or twisting it, the axis of rotation will always point in the same original direction!!!!

So you can now fix the base of your gyroscope to, say, an airplane and fix the axis of rotation with the ground direction and even if your airplane twists and turns you’ll always know where the ground (direction) is!!!

hope it helps! :-)