# Help on dc motor question mechanical engineeringWatch

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#1
A DC servo motor mist accelerated from rest to 30 rad/sec in 3 sec. the rotating mass has a moment of inertia of 5 kgm^2. The load torque is 20NM and the friction torque is 1.2NM. The damping coefficient is 0.05Nm/s radian. The torque constant is 120Nm per ampere. Determine the required current just before the acceleration.
Can some help me to calculated
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#2
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2 years ago
#3
(Original post by Rashik gurung)

Regarding your questions, can you post your working please of what you have done so far? That way hopefully someone will be able to help you with where you are going wrong or where you need to go next.
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2 years ago
#4
(Original post by Smack)

Regarding your questions, can you post your working please of what you have done so far? That way hopefully someone will be able to help you with where you are going wrong or where you need to go next.
To add to what Smack has said, I've calculated them just now myself and obtained the answers.

To give you a clue, start with the simple mechanical definition of power, that is:

then use the basic definition of efficiency to obtain the input current at the given voltage:

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