Find moment of inertia via torque and acceleration parameter

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SUMMARY

The discussion focuses on calculating the moment of inertia of a motor given a constant torque of 4 Nm and a speed of 1717 rpm reached in 4 seconds. The relevant equations include T = J(eff) * dw/dt and J = kg*M^2, where J represents moment of inertia. The confusion arises from the units of moment of inertia being stated as Nm·s², which is clarified as equivalent to kg·m². The user successfully identifies how to calculate dw/dt, indicating a resolution to their initial uncertainty.

PREREQUISITES
  • Understanding of torque and its units (Nm)
  • Familiarity with rotational dynamics and moment of inertia
  • Basic knowledge of angular velocity and its calculation
  • Proficiency in applying Newton's second law for rotation
NEXT STEPS
  • Study the relationship between torque, moment of inertia, and angular acceleration
  • Learn how to convert between different units of angular velocity (e.g., rpm to rad/s)
  • Explore the implications of damping in motor dynamics
  • Investigate advanced topics in electric drives and motor control systems
USEFUL FOR

Students in mechanical engineering, particularly those studying electric drives, as well as professionals involved in motor design and analysis.

D.B0004
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Homework Statement


2-1. A constant torque of 4 Nm is applied to an unloaded motor at rest at time t = 0. The motor reaches a speed of 1717 rpm in 4 s. Assuming the damping to be negligible, calculate the motor inertia in Nm·s2.

Homework Equations


T = J(eff) * dw/dt
J = kg*M^2

The Attempt at a Solution


I have NO clue where to start. First question - why is the motor inertia units stated as Nm*S2? I thought moment of inertia was only kg*m^2 (m = meters).
Second question - can someone point me in the right direction? I have been reading for hours. I know this is simple I'm just missing a link. Thanks for the help.
Also the problem seems basic but I posted it in this section because its for a 4000 level course - Electric Drives. Let me know if it should be elsewhere.
 
Physics news on Phys.org
1 N = 1 kg * 1 ms-2

In your first relevant equation, how would you calculate dw/dt?
 
Wow. I feel like an idiot. Got it. Thanks.
 

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