A disc in space will rotate or not?

In summary, the question is whether a uniform thin flat isolated disc will rotate with acceleration or only accelerate when a force is applied at a distance of half its radius from the center. The equations have not been provided, but based on the author's attempt at a solution, it is concluded that the disc will not rotate. The concern about the chosen center of rotation is raised, suggesting confusion on the topic. The reader is encouraged to consider the motion of the disc's center of mass when it is rotating about a point on its edge.
  • #1
mooncrater
217
18

Homework Statement


Consider this question:
"A uniform thin flat isolated disc is floating in space. It has radius R and mass m. A force F is applied to it at a distance ##d=\frac {R}{2}## from the centre of the disc. So,
Will the disc rotate with accelerating in the direction of force or it won't rotate and will accelerate only?

Homework Equations

The Attempt at a Solution


I think it won't rotate. If it will then it's not clear which point is chosen as the centre of rotation. If it is the centre of the disc, then why is it chosen? I am confused about this thing.
 
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  • #2
Why don't you just set up the equations, and see what they tell you?

Chet
 
  • #3
mooncrater said:

Homework Statement


Consider this question:
"A uniform thin flat isolated disc is floating in space. It has radius R and mass m. A force F is applied to it at a distance ##d=\frac {R}{2}## from the centre of the disc. So,
Will the disc rotate with accelerating in the direction of force or it won't rotate and will accelerate only?

Homework Equations

The Attempt at a Solution


I think it won't rotate. If it will then it's not clear which point is chosen as the centre of rotation. If it is the centre of the disc, then why is it chosen? I am confused about this thing.

Suppose a disc is rotating about a point on its edge. What can you say about the motion of its centre of mass?
 
  • #4
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Related to A disc in space will rotate or not?

1. Will a disc float in space?

No, a disc will not float in space because there is no air resistance or buoyancy to keep it afloat. It will continue to move in a straight line or rotate unless acted upon by an external force.

2. What causes a disc to rotate in space?

A disc in space will rotate due to its angular momentum. This is the product of its mass, velocity, and distance from the center of rotation. In the absence of any external forces, the disc will continue to rotate at a constant speed and direction.

3. Can a disc rotate in space forever?

In theory, yes. As long as there are no external forces acting on the disc, it will continue to rotate at a constant speed and direction due to its angular momentum. However, in reality, there may be very small external forces, such as gravitational or magnetic forces, that may eventually slow down or alter the rotation of the disc.

4. What factors can affect the rotation of a disc in space?

The rotation of a disc in space can be affected by external forces such as gravity, magnetic fields, and collisions with other objects. Additionally, the shape and size of the disc, as well as its initial rotational speed, can also impact its rotation in space.

5. Is the rotation of a disc in space the same as on Earth?

No, the rotation of a disc in space is not the same as on Earth. In space, there is no air resistance or friction, so the disc will continue to rotate at a constant speed in the absence of external forces. On Earth, the rotation of a disc is affected by air resistance and friction, causing it to eventually slow down and stop.

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