Hello everyone. I wonder if someone could help me choose the proper motor for a project I am working with.

So the idea is to move a lever of 10cm (which rotates from one end) using a servo ou step motor. My doubt is about selecting the right amount of torque necessary from the motor.

Let's say the lever has to be pushed with same force as to lifting 10kg. So, my reasoning is as follows:

10Kg needs around 98.0665 ~ 100 Newtons of force.

It is known that Torque = radius x Force, thus Torque = 0.1m * 100N = 10Nm (Assuming no loss of force due to vector directions).

Thus, this tells me I need a motor of at least 10Nm. But I should double it to be safe.

Conclusion,
A servo/step motor with Torque of 20Nm or ~200kg-cm, and a 10cm arm, should be enough to lift 10kg.

The speed at which you want it to move. Servos are spec'd at some number of seconds / 60 degrees*

Then you need to calculate the mechanical power (P=Tw, Watts= Nm x rad/sec*) and then make a stab at the electrical power required allowing for some losses in the conversion process, and then arrive at the electrical current from P=VI.

since a radian is 57degrees, seconds/60 is not a million miles off seconds/rad, so the inverse of that is close to rad/sec.