I didn't understand one thing. If the magnitude of torque depends on the distance of the mass from the axis of rotation, doesn't this contradict the principle behind keeping the door handle away from the hinges so that the requisite torque can be achieved by applying less force?
Rotational inertia is an internal property of an object. Torque is something that acts from outside. Rotational inertia is very slighlty larger if the handle is far from hinge, however, for the same force applied, the torque will be larger if applied farther from the hinge, so the door increases the rate at which it rotates more easily if the force is applied farther from the hinge.
Chris, I absolutely love your videos. Your particle physics ones were a lifesaver. Will you be doing videos for B.2?
+thejorgegeorge30
Good to hear. B.2 Thermodynamics is done...google doner thermodynamics.
great video, keep up !
I didn't understand one thing.
If the magnitude of torque depends on the distance of the mass from the axis of rotation, doesn't this contradict the principle behind keeping the door handle away from the hinges so that the requisite torque can be achieved by applying less force?
Rotational inertia is an internal property of an object. Torque is something that acts from outside. Rotational inertia is very slighlty larger if the handle is far from hinge, however, for the same force applied, the torque will be larger if applied farther from the hinge, so the door increases the rate at which it rotates more easily if the force is applied farther from the hinge.
Hey Chris, will the rotational inertia's formula be provided in an IB exam? Or do we have to memorise all the different formulas?
They will tell you the rotational inertia of any object that is not a point mass (MR^2) within the question. Point mass is given in the data book.
Okay, thank you.
Thanks