# Will the spinning gyroscope make the plumb fall slower?

• I
• SpaceThoughts
In summary, a gyroscope will slow down the falling plumb if the gyroscope is spinning. However, it is not clear how the rate of the plumb's descent is related to the spinning of the gyroscope.f

#### SpaceThoughts

When winding a bike wheel up in an elastic double string in the ceiling, and then let the wheel spin vertically, it unwinds more slowly than if it was not spinning. I tried it.
But it if a spinning disk is placed in a solid construction like this (photo attached) , and can only rotate horizontally as the blue plump falls, will the plumb likewise fall more slowly than if the gyroscope was not spinning? If no, why is the gyroscope not working the same way as with the string in the ceiling?
I tried to simulate the situation in the photo with a moving front wheel of a bike, by could not detect a slower movement of the bike wheel, spinning versus not spinning.
Is that because the gyroscopic inertia (not the forces) is too small compared to the weight of the handlebars etc?
If the spinning gyroscope does slow down the falling plumb, how do I mathematically connect the speed of the wheel with the speed of the plumb? Please see my previous question.

Calculate with the inertial momentum of the gyroscope. Spinning up a gyroscope is like a mass being accelerated; it needs to 'use' some of that force for its angular acceleration.

Spinning up a gyroscope is like a mass being accelerated; it needs to 'use' some of that force for its angular acceleration.
If you apply an off-axis force to an object, none of that force is "used up". All of the force goes into linear acceleration. That's conservation of momentum in action. All of the force (times moment arm) also goes into angular momentum. That's conservation of angular momentum in action.

Both laws apply. Both apply to the full force.

That said, I can make neither head nor tail of the mechanism described in the original post. It is word salad and an inscrutable drawing to me.

If you apply an off-axis force to an object, none of that force is "used up". All of the force goes into linear acceleration. That's conservation of momentum in action. All of the force (times moment arm) also goes into angular momentum. That's conservation of angular momentum in action.

Both laws apply. Both apply to the full force.

That said, I can make neither head nor tail of the mechanism described in the original post. It is word salad and an inscrutable drawing to me.
I took the description to mean there are two strings wound around the spindle of the wheel, and thus as the wheel falls so the wheel will spin up (hence the 'gyroscope' reference in the thread title) according to the tension in the strings.

The rate at which all that would happen would be a function of the radius of the spindle about which the strings are coiled.

Obviously, the wheel will drop slowly as the gravitational potential energy is largely converted into inertial rotational kinetic energy.

I thus took the second description to mean likewise, but that the 'gyroscope' is now fixed and the tension horizontal to a mass which can fall vertically.

If it was not 'that', then yes, forget what I said.