Ok so I have never really used motors before so I have no idea what I am doing, but I was wondering how to calculate how much weight a motor could move.

Say I have a trolley that weights ~300kg, and I attached a motor to each of its 4 wheels how would I calculate if it would move/what would be needed to move it, and how would I know the RPM of the motors. (Friction can be ignored and it would be on a flat surface)

Also, if I added 4 more motors to turn the wheels, since its just moving a small wheel and it wont be supporting the weight, could it be weaker than the other motors, or would the force that the wheel is experiencing from the trolleys weight effect the turning of the motor.

okay, so I have spent a few more hours researching and I think this is how it works:

Friction will matter, because otherwise the thing wont require force to move sideways if its frictionless, so I will assume a friction co-efficient of 0.4 (like on concrete).

If the trolley weighs 300kg, then the normal force should be the same (its equal to the downward force, which is the weight)

Using https://omnicalculator.com/physics/..., it says that it will then have an overall friction of 120N, which is what the motors will be pulling. Since there is 4 motors, that means 30N each.

The motor would be attached to the side of the wheel, so will have a radius of 1cm, meaning I would need a motor with torque 30N-cm (about 3kg-cm) on each wheel, which is 0.3N-m, or 30g-m.

I don't know if this is all right, so if someone could still lmk if anything is wrong that would be nice tbh.