Centripetal Velocity Calculation?

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Discussion Overview

The discussion revolves around calculating the exit speed of an object dropped into a spinning container operating at 5000 RPM with a radius of 120mm. The context includes a machine designed for wear testing, where a rock is dropped into a spinning rotor that impacts a test specimen.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Kevin seeks assistance in calculating the exit speed of a one-gram object dropped into a spinning container.
  • One participant argues that more details are needed about the mechanism of how the mass is dropped and exits the container, suggesting that the speed may not depend on the mass if the container is significantly heavier.
  • Another participant mentions that the final tangential speed is equal to the speed of the channel ends and notes that the final radial speed may depend on friction, proposing to integrate the centrifugal acceleration in the rotating frame.
  • A similar point is reiterated regarding the relationship between the tangential and radial speed components, emphasizing the role of friction.

Areas of Agreement / Disagreement

Participants express differing views on the necessary details for calculating the exit speed, and while some agree on the relationship between speed components, no consensus is reached on the overall calculation method or assumptions involved.

Contextual Notes

The discussion lacks specific details about the mechanism of the object’s drop and exit, which may affect the calculations. There are also unresolved aspects regarding the role of friction in determining the final speeds.

Kevin B2
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I am wondering if someone can show me how to calculate the exit speed of an object if it is dropped into a container which is spinning at 5000 rpm and has a radius of 120mm. Let us assume the object weighs one gram.
I am building a machine for wear testing. rock/water is supplied to the centre of a spinning rotor and is impacted upon a test specimen, mounted at the exit port.
Thank you for your time,
Kevin
 
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This is impossible without many more details about the mechanism. How is the mass dropped into the container, how does it hit the container, how does it leave again, and so on.
If the container is heavy enough (compared to the dropped object), the speed won't depend on the mass of the object.
 
I cannot show the detail due to proprietary reasons but essentially this is what I am describing, a rock dropped into the center of a stainless steel channel, spinning at 5000 RPM;
https://lh3.googleusercontent.com/9-tYG8bqb8-6z8x6HuCUJBWsmZSGc5vHMBU-mH63KaIWY-6hQFXO-KylOch9CpssdgouIfY60JPtx7JOvGXP4sGKmyUYgohlFAhbg1XVF0bPblQkTkHi7Lg6vl0EHwR3vNcB32VWLhezY-VSRetPP7GtCU5CIAd_pKm6isw1gSbc-CTeGrel3eq-hyYW1dJbzCB5S3lat4NlLaCT8tGNEF4Wyq-E7AkKuU4gyiFgB1Y2uOxUOtrmHo6DlI4crajlM-ZzgNicCiM-7xG2_8kEdaFEMUCz7uYanyiDGNkdgJK-GbbHOzFw0dTMEIr1ew7IYUcpRMcZ1NnJoH4JDLoUQ8EbtZR8T6gzE_mXdtCh-RgSf4-MNwnt5WBLrzdLbOTpv2tWK2pKXD5yBPbiKxSNEp__Bn_rmsMmGrtaT0SHRYRLX24tldTIX5YVQVwSTkSA9sfXQ3CPxcvI_8j-lwYSJrDKCpzyP1GltqN1WDwzc3MO_EgdI8uECouiOkY6n8-KACE9U3cHH6fP-t7BqkiuWk1xnC707hfZcxkVc23cg76_F6Lw3ZSBSrDY1s7EuhhzhKk=w699-h646-no

Thanks again,
 
Kevin B2 said:
I cannot show the detail due to proprietary reasons but essentially this is what I am describing, a rock dropped into the center of a stainless steel channel, spinning at 5000 RPM;
https://lh3.googleusercontent.com/9-tYG8bqb8-6z8x6HuCUJBWsmZSGc5vHMBU-mH63KaIWY-6hQFXO-KylOch9CpssdgouIfY60JPtx7JOvGXP4sGKmyUYgohlFAhbg1XVF0bPblQkTkHi7Lg6vl0EHwR3vNcB32VWLhezY-VSRetPP7GtCU5CIAd_pKm6isw1gSbc-CTeGrel3eq-hyYW1dJbzCB5S3lat4NlLaCT8tGNEF4Wyq-E7AkKuU4gyiFgB1Y2uOxUOtrmHo6DlI4crajlM-ZzgNicCiM-7xG2_8kEdaFEMUCz7uYanyiDGNkdgJK-GbbHOzFw0dTMEIr1ew7IYUcpRMcZ1NnJoH4JDLoUQ8EbtZR8T6gzE_mXdtCh-RgSf4-MNwnt5WBLrzdLbOTpv2tWK2pKXD5yBPbiKxSNEp__Bn_rmsMmGrtaT0SHRYRLX24tldTIX5YVQVwSTkSA9sfXQ3CPxcvI_8j-lwYSJrDKCpzyP1GltqN1WDwzc3MO_EgdI8uECouiOkY6n8-KACE9U3cHH6fP-t7BqkiuWk1xnC707hfZcxkVc23cg76_F6Lw3ZSBSrDY1s7EuhhzhKk=w699-h646-no

Thanks again,

The final tangential speed is the speed of the channel ends. The final radial speed will depend on friction in the channel, but ignoring that, you would just integrate the centrifugal acceleration in the rotating frame.
 
A.T. said:
The final tangential speed is the speed of the channel ends. The final radial speed will depend on friction in the channel, but ignoring that, you would just integrate the centrifugal acceleration in the rotating frame.
Ignoring friction, there is an interesting fixed relation between the two speed components.
 
Thank you for your insight.
 

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