# Lect_22 - ACT Spheres Two spheres have the same radius and...

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Lecture 22 Torque ACT: Spheres Two spheres have the same radius and equal masses. One is made of solid aluminum and the other is a hollow shell of gold. Which one has the biggest moment of inertia about an axis through its center? A. Solid Al B. Hollow Au C. Both the same Hollow gold Solid aluminum Mass is further away from the axis 2 tan Fr mr α = An intuitive approach to torque A particle of mass m is constrained by a massless rod of length r to move in circles about point P. A force F is applied on the particle.This is the only force applied on it. What is the angular acceleration of the system? tan tan produces a tangential acceleration: tan tan Fma = I t ar = tan Fmr = τ = P Torque tan = Directions: Both and point out of the screen. G rF × G G = zz G G G θ sin == × G G Newton’s second law for rotations G G G For each force on a system, the torque depends on the point on which it is applied τα net, i, all forces z The angular acceleration will be the result of adding all these torques: G G net Note: In general, torque by the net force (What would be the ?!?)

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## This note was uploaded on 04/16/2008 for the course PHYSICS 221 taught by Professor Johnson during the Fall '06 term at Iowa State.

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Lect_22 - ACT Spheres Two spheres have the same radius and...

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