Rotational Motion: Calculating Time to Reach 750 RPM

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Homework Help Overview

The discussion revolves around a problem in rotational motion involving a motor-driven disk that accelerates to a specified speed of 750 RPM. Participants are exploring the relationship between power, torque, and time in this context.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants express uncertainty about how to begin solving the problem, particularly regarding the connection between horsepower and torque. There are inquiries about calculating time without knowing distance or acceleration. Additionally, questions arise about the energy of the disk at operating speed and how that relates to finding time.

Discussion Status

The discussion is ongoing, with participants seeking clarification on the relationships between power, energy, and time. Multiple interpretations of how to approach the problem are being explored, but there is no explicit consensus on a method yet.

Contextual Notes

Participants are grappling with the implications of the given parameters, such as the mass of the disk and the motor's horsepower, while also considering the absence of certain information needed for a complete analysis.

hannah12345
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Homework Statement


A 1.5 hp motor drives a machine disk having a mass of 4.5 kg and a diameter of .4 m from rest to a speed of 750 rpm. How long does it take to reach the operating speed?

Homework Equations


angular momentum
torque

The Attempt at a Solution


I'm not really sure where to start with this problem. I don't know how to find time without distance or acceleration. I tried solving for acceleration but I'm not sure how horsepower relates to torque.
 
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How much energy will the disk have at operating speed?
 
How would I use that to find time?
 
hannah12345 said:
How would I use that to find time?
What is the relationship between power, energy and time?
 

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