Angular acceleration of a motor

In summary, the conversation discusses a motor with an armature of 250kg and a diameter of 30cm, with a rotational inertia of 22.5 kg-m^2. It is assumed that the mass of the armature is evenly distributed. The motor is accelerating unloaded with a constant torque of 120 N-m, and the question is asked how long it will take for the unloaded armature to accelerate from 0 to 3000 rpm. The solution involves converting RPM to rad/s and using rotational kinematic equations or the fact that net torque equals the time rate of change of angular momentum.
  • #1
Dangousity
6
0

Homework Statement


I have a motor, with an armature that has a mass of 250kg , and a diameter of 30 cm. Assuming the mass of the armature is evenly distributed, the rotational inertia of the armature is 22.5 kg-m^2.
Now the motor accelerating unloaded, with armature current regulated so that the armature develops a constant torque of 120 N-m, would be coming up to speed at 35.8 rad/sec^2? (Did I get this wrong?)
Assume the torque stays the same, How long will it take for the unloaded armature to accelerate from 0 to 3000 rpm.

Homework Equations


T=Ia 22.5 kg-m^2(3000(pie)-15cm(pie))/(T)
22.5(3000(pie)-.15m(pie))/(T)

I think I am doing something wrong here cause I get stuck here.

The Attempt at a Solution

 
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  • #2
Mmm. Pie...

It looks like you're trying to convert RPM to rad/s? I don't quite follow your equations.

3000 revolution/min * 2pi rad/revolution * 1 min/60 s

Should give you your angular speed.

To figure out how long it takes, you can probably use the fact that net torque = dL/dt (the time rate of change of angular momentum) or you could use rotational kinematic equations to solve for the time.
 
  • #3
JaWiB said:
Mmm. Pie...

It looks like you're trying to convert RPM to rad/s?

Correct, I am attempting to do that
 

Related to Angular acceleration of a motor

1. What is angular acceleration?

Angular acceleration is the rate of change of angular velocity, or how quickly an object's rotational speed is changing. It is typically measured in radians per second squared (rad/s^2).

2. How is angular acceleration different from linear acceleration?

Angular acceleration is a measure of how quickly an object's rotational speed is changing, while linear acceleration measures how quickly an object's linear velocity is changing. Angular acceleration is a vector quantity, meaning it has both magnitude and direction, while linear acceleration is a scalar quantity with only magnitude.

3. How is angular acceleration of a motor calculated?

The formula for calculating angular acceleration is: angular acceleration (α) = change in angular velocity (Δω) / change in time (Δt). This can also be written as α = (ω₂ - ω₁) / (t₂ - t₁), where ω is the angular velocity and t is the time.

4. What factors can affect the angular acceleration of a motor?

The angular acceleration of a motor can be affected by a number of factors, including the torque applied to the motor, the moment of inertia of the rotating parts, and any external forces acting on the motor. The type and size of the motor can also affect its angular acceleration.

5. Why is angular acceleration important in motor control?

Angular acceleration is important in motor control because it allows us to understand and predict how quickly a motor will change its rotational speed. This is crucial for controlling the movement and speed of rotating parts in various applications, such as in robotics, machinery, and vehicles.

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