# Torque needed to open a door!

My door is 2000kg, it is 3m wide, 4m high and is on a hinge. for the moment i am saying that friction is negligable. How much torque is required to open my door. I have already said that the torque needed to open the door is acting through the C.O.G so it is 2000(1.5)(9.81), i don't know if that is correct though, please help :) If I can find this then I can find out the angular velocity and acceleration

russ_watters
Mentor
If friction is negligible and the door hinges are perfectly aligned, then any amount of torque will open the door.

How fast do you want the door to open?

want door to open in ten seconds.

You could apply the angular equal of Newton's laws for linear motion:

F = ma
torque = moment of inertia X angular acceleration
angular acceleration = change in angle / change in time.

Let me know if you need any help with this.