# Solving Torque & Rotation with DC Motor: Scott's Project

• salph
In summary, the person is working on a project involving 6 circular platforms that need to be rotated in the same direction using a gear and chain system. They are looking for a suitable DC motor and torque to rotate the platforms at 12 RPM with 600 grams on each platform. They also mention wanting to use D cell batteries and are open to other lightweight options. They note that the dimensions of the platforms are needed and mention calculating the moment of inertia and the necessary torque. They also discuss the option of using an oscillator to control the motor's speed.
salph
Hello all. I am working on a project and am a little lost on the physics end. Basically, I have 6 circular platforms that need to be rotated in the same direction. I figured I would have a gear under each and a chain connecting them similar to a bicycle chain. I need to figure out what DC motor to get and how much torque I will need if each platform had 600 grams on it and needed to rotate at a speed of 12 RPM.

Other things to note: Power Source - would like to be d cell batteries. Was hoping for 2 maybe 4. Open to other options that are light and small.

Thanks for any help.
-Scott

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You need the dimensions of the platform, as well.

If you're speaking of circular platforms, 600 grams each, each platform's moment of inertia can be found by:

I = mr^2/2

You add them up to get the overall moment of inertia (or multiply by 6 in this case).

The torque you need will depend on how fast the platforms have to get up to speed. (Torque equals moment of inertia times angular acceleration). Once up to speed, the motor only has to overcome the friction of the system.

Either the gearing has to turn the motor's speed into 12 RPM (with each additional gear increasing your moment of inertia, etc), or you need to turn the motor off when the speed is too fast and turn it back on when the speed is too slow (i.e. - an oscillator that puts pulses out 12 times a minute and some electronics to turn the motor off when you get two consecutive pulses from the gear system and turn the motor on when you get two consecutive pulses from the oscillator).

## 1. What is torque and how does it relate to DC motors?

Torque is a measure of the twisting force that can cause an object to rotate. In DC motors, torque is produced by the interaction between the magnetic fields of the stator (stationary part) and the rotor (rotating part).

## 2. How can torque and rotation be calculated for a DC motor?

Torque can be calculated by multiplying the force applied to the motor by the distance from the center of rotation to the point where the force is applied. Rotation can be calculated by dividing the torque by the moment of inertia of the motor.

## 3. What factors affect the torque and rotation of a DC motor?

The torque and rotation of a DC motor can be affected by factors such as the voltage and current applied to the motor, the type and strength of magnets used, and the design and construction of the motor.

## 4. How can torque and rotation be optimized in a DC motor?

To optimize torque and rotation in a DC motor, factors such as the motor's design, type and strength of magnets, and the voltage and current applied can be adjusted and fine-tuned. Additionally, reducing friction and resistance within the motor can also help improve its performance.

## 5. What are some real-world applications of solving torque and rotation in DC motors?

DC motors are commonly used in various applications such as electric vehicles, industrial machinery, and household appliances. By understanding and solving for torque and rotation, engineers can design and optimize DC motors for specific purposes, such as providing enough power to move heavy loads or achieving precise and smooth rotations in robotics and automation systems.

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