Torque application.

Teachme

Hello. I am trying to learn how to apply my knowledge of torque to a real life problem but i'm not quite sure how. I have attached a picture describing what I am trying to do. I would be very appreciative if anyone would take the time to take a look at what I have done and see if my view of torque is correct. Mostly just want to know if I have put my torque vector in the right location I have included drawings along with my questions that should make understanding easier.

Please don't give me a Wikipedia link because that is useless for me. Iv'e read it a million times. I have tried countless sources, but I have found none that use real applications.

Please let me know if I can clarify anything.

Thank you very much for reading.

Attached Thumbnails

 

tiny-tim

Hello Teachme!
Right direction , but wrong line.

torque is proportional to rate of change of angular momentum,

and angular momentum is always in the direction of the axis of the cylinder, so torque is also.

But there is an unknown reaction force on the axle, so to avoid this coming into the equations, you will always take moments (torques) about the axle, so that's where your torque arrow should be shown.

Teachme

Mess up

Teachme

Oh never mind. I see it is suppose to be in the center of the barrel. Correct?

tiny-tim

Hi Max!
I don't understand.

Your picture showed it along the x-axis, not the z-axis.

And as i said, it should be along the axle (the centre of the barrel).

tiny-tim

Yes.