Reaction forces on a gyroscope

In summary: For reaction at O, what is the tension in the rod?I agree with you, I think it should say "axle". The question says that the disk rolls without slipping.If it is restricting the motion of the disk then it must be exerting a force.The only forces that produce torque in this case are the normal force on ##C## and weight, so we can get the value of the normal forceAnd what are you equating Mz to in terms of the reaction force at C?
  • #1
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Homework Statement
An homogenous disk of radius ##r## and mass ##m## rotates about the point ##O## with ##\omega_2## and is restricted to move in a horizontal plane. It also rotates about the point ##G## with constant angular velocity ##\omega_1##. Determine the reaction forces on ##A##, ##O## and ##C##. Consider that the bar of length ##L## has no mass.
Relevant Equations
##\Sigma M=I \dot\omega +\omega × I \omega##
I know that
##\vec{v_c}=(\omega_1;-\omega_2;0)×(L;-r;0)=0##
So ##\omega_2=\frac{r\omega_1}{L}##

Then, using the system of coordinates shown in the picture and ##\Sigma M_z## I can find the reaction force in ##C##.

But how can I find the reaction forces on ##A## and ##O##? I mean, what system should I use to apply Euler equations?
 

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  • #2
The question wording doesn't match the diagram well. Shouldn't it say that the axle of the disk "rotates about the point O with ω2 and is restricted to move in a horizontal plane"?
No mention is made of friction. You are assuming no slippage, but if there is friction that acts towards O, parallel to the tension in the rod, then it is unclear how to apportion the nett force in that direction between the two.
What did you get for the reaction at C?

For reaction at O, what is the tension in the rod?
 
Last edited:
  • #3
I agree with you, I think it should say "axle". The question says that the disk rolls without slipping.
I thought that there was no tension, I considered that the rod was there just to restrict the motion of the disk.
 
  • #4
Like Tony Stark said:
I agree with you, I think it should say "axle". The question says that the disk rolls without slipping.
I thought that there was no tension, I considered that the rod was there just to restrict the motion of the disk.
If it is restricting the motion of the disk then it must be exerting a force.
What would the disk do if no rod?
 
  • #5
Using the fact that ##\omega_1, \omega_2=constant## and that the axis shown are the principal axis, I got:
##\Sigma M_z=\omega_1 \omega_2 (I_x-I_y)##
The only forces that produce torque in this case are the normal force on ##C## and weight, so we can get the value of the normal force
But this system that I've chosen doesn't allow me to find the reaction force on ##A## and ##O##.
 
  • #6
Like Tony Stark said:
Using the fact that ##\omega_1, \omega_2=constant## and that the axis shown are the principal axis, I got:
##\Sigma M_z=\omega_1 \omega_2 (I_x-I_y)##
And what are you equating Mz to in terms of the reaction force at C?

There's nothing to stop you taking moments about another axis.
 

1. What is a gyroscope and how does it work?

A gyroscope is a spinning wheel or disk that is mounted on an axis and used to maintain orientation or provide stability in navigation or other applications. It works by utilizing the principle of angular momentum, where the spinning motion of the gyroscope resists any external forces acting on it, allowing it to maintain its orientation.

2. How does a gyroscope experience reaction forces?

A gyroscope experiences reaction forces due to the conservation of angular momentum. As the gyroscope spins, it creates a force that is perpendicular to its axis of rotation. When an external force is applied to the gyroscope, it experiences a reaction force that is equal and opposite to the external force, causing it to resist any changes in its orientation.

3. What factors affect the magnitude of reaction forces on a gyroscope?

The magnitude of reaction forces on a gyroscope is affected by several factors, including the mass and speed of the gyroscope, the direction and magnitude of the external force, and the moment of inertia of the gyroscope.

4. How are reaction forces on a gyroscope used in real-world applications?

Reaction forces on a gyroscope are utilized in a variety of real-world applications, such as in navigation systems, spacecraft attitude control, and stabilization of cameras and drones. They are also used in gyroscopic instruments, such as gyrocompasses and gyroscopes in airplanes, to measure and maintain orientation.

5. Can reaction forces on a gyroscope be manipulated or controlled?

Yes, reaction forces on a gyroscope can be manipulated or controlled by adjusting the speed and direction of the gyroscope's spin, as well as by applying external forces in specific directions. This allows for precise control and stabilization in various applications.

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