How Much Torque to Spin a Disk at 30,000 RPM?

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SUMMARY

The discussion centers on calculating the torque required to spin a disk with a mass of 54.3 grams at 30,000 RPM. It is established that no torque is needed to maintain the disk's speed on frictionless bearings; however, torque is necessary to accelerate the disk from rest and to overcome friction and air resistance. The key formula for torque in this context is not explicitly provided, but understanding the relationship between torque, angular acceleration, and friction is crucial for accurate calculations.

PREREQUISITES
  • Understanding of basic physics concepts such as torque and angular velocity.
  • Familiarity with the formula for torque: τ = I * α, where τ is torque, I is moment of inertia, and α is angular acceleration.
  • Knowledge of friction dynamics, including bearing friction and air resistance.
  • Ability to convert mass units, specifically grams to kilograms for calculations.
NEXT STEPS
  • Research the moment of inertia for different disk shapes to apply in torque calculations.
  • Learn about the effects of friction in mechanical systems, particularly in bearings.
  • Explore the relationship between torque, angular acceleration, and RPM in rotational dynamics.
  • Investigate methods for calculating air resistance on spinning objects at high speeds.
USEFUL FOR

Engineers, physicists, and hobbyists interested in mechanical design, particularly those working with motors and rotational systems requiring precise torque calculations.

bcjirvin
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Hi, I'm new to this forum so I'm not exactly sure if I'm posting in the right place. But I have a question about torque.

Okay so, how much torque would a motor need to supply to be able to spin a disk with a mass of 54.3 g at 30,000 RPM?

If you could also provide and explain the formula for determining torque that would be great.

Thanks!
 
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bcjirvin said:
Hi, I'm new to this forum so I'm not exactly sure if I'm posting in the right place. But I have a question about torque.

Okay so, how much torque would a motor need to supply to be able to spin a disk with a mass of 54.3 at 30,000 RPM?

If you could also provide and explain the formula for determining torque that would be great.

Thanks!

Welcome to the PF.

What is the context of the question? It takes no torque to spin a disk on frictionless bearings at a constant RPM. The torque would be needed to spin the disk up from zero to final speed, and to overcome bearing friction and any air resistance involved.

Also you need units on the mass that you supplied...
 

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