The physics of flywheel launchers (like tennis ball shooters)

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Discussion Overview

The discussion revolves around the physics of flywheel launchers, specifically focusing on the mechanics of how rotational kinetic energy and angular momentum interact with projectiles like tennis balls. Participants explore various factors affecting projectile velocity, including inertia, friction, compression, and torque, while questioning the relationships between these variables.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants propose that the final velocity of the projectile is influenced by multiple factors, including inertia, elasticity, and the moment of inertia of the wheel.
  • There is a question about the role of slippage due to friction, with some arguing that more slippage may be beneficial while others suggest that no slippage allows for better rolling.
  • Compression of the projectile is discussed, with participants questioning how it affects momentum and energy efficiency, particularly in comparison to other shapes like disks or toruses.
  • Some participants assert that RPM and tangential velocity are more critical to final velocity than torque, while others challenge this view, suggesting that torque should play a significant role.
  • There is a discussion about how torque is consumed in providing impulse to the projectile, raising questions about the relationship between torque, force, and velocity.
  • One participant suggests simplifying the analysis by considering a two-wheel launcher, which may provide a clearer understanding of the forces at play.
  • Concerns are raised about how compression costs energy and how momentum is conserved or lost during the process of acceleration and release.
  • Some participants argue that friction acts as a clutch during the projectile's contact with the wheels, which is essential for transferring energy effectively.

Areas of Agreement / Disagreement

Participants express differing views on the significance of torque versus RPM in determining final velocity, with no consensus reached on the primary factors influencing projectile acceleration. The role of friction and compression also remains a topic of contention, with various interpretations of their effects on energy transfer and momentum.

Contextual Notes

Participants highlight the complexity of the interactions between torque, inertia, friction, and compression, indicating that assumptions about these relationships may vary. The discussion reflects a range of interpretations regarding the mechanics involved in flywheel launchers.

  • #61
cardboard_box said:
I already know some of these variables, but I am not fully sure I get every effect of them and I still don't understand the importance of RPM.
cardboard_box said:
so for example, if you are given a projectile which you know everything you want about, and are told to fire it at this and this velocity and fire this and this of them at this and this rate, how do you decide what wheel do you use?

...how exactly do I go about building such a function? specifically how does the velocity of the wheel change the velocity of the ball?
You solve the problem as described in Post #38. Is the real here here that you don't know how to solve that problem?
 

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