# Torque on a horizontal axis

Andrea Vironda
Hi,
I'm making some confusion about statical and dynamic behavior.
if i have a body distant from the rotational axis, i have a static torque for maintaining it on position (i suppose ##\vec g \perp \vec r##).
But if a supply more torque i accellerate the body. How can i quantify this accelleration? it will be not constant because ##\vec g## is no more perpendicular to ##\vec r##.
i would obtain ##C(\theta)=mg(\theta)r+I\ddot \theta##. How can a motor mantain a constant accelleration?

Last edited:

## Answers and Replies

Science Advisor
Gold Member
How can a motor mantain a constant accelleration

I don't understand the problem - a suitable choice of motor and control system will do anything that you want it to do .

Is your question really meant to be about how to determine the variable driving torque needed to maintain a constant angular acceleration ?

Last edited:
Andrea Vironda
I don't understand the problem - a suitable choice of motor and control system will do anything that you want it to do .

Is your question really meant to be about how determine the variable driving torque needed to maintain a constant angular acceleration ?
i would to know if my expression in ##C(\theta)## is correct

Dr.D
What do you intend your expression C(theta) to represent?

Where does a motor enter into the problem as originally described?

Andrea Vironda
hi, ##C## is a torque, ##coppia## in italian language. It's the torque expression as ##f(\theta)##

Dr.D
You need to understand that g is not a function of theta; g is a constant. What you need is the component of g that acts perpendicular to the radius. Draw a diagram with labels and it should all become clear.