So I'm going to take a PS my Origin and so now is the question. what is Tarque relative to point p well. it's are cross Ref or is this distance which is be F is Angie but has a cross product. so I have to take sign of this angle into account. there is the magnitude of the pork and the magnitude of that talk them. according to my rotationally, criminal have equal to me, equal the moment of mertia for rotation. about that point p times say that double dot. whatever it is a restoring tort torque you can do that was your right hand, wherever where you have learned how to do that the torque is in the blackboard perpendicular to the blackboard. in the blackboard are cross f in the black. I have rotated counter clockwise which is a factor out of the blackboard. So, one is like this and the other like this that is like saying torque is restoring the same reason why we wrote down F equals minute KX with this spring is why we now right this equal mme is this talking two come the direction of the factors. So, this is the differential equation that you would have to so and is now we go to small angle approximation. Then, the sign of a to goes to fade out of state is radiance and so I can really write down these data double dot plus be am 6 divided by the moment of inertia park point p time data equal0 now small angle approximation we have the differential equation which is Agam piece of cake simple harmonic oscillation and so the simple harmonic oscillation solution must be paid up is some maximum angle theta 0 time the cosine only got people ask why by this omega is the crew