Youd probably add in a safety factor of at least 2x however A 00 00 2 2 C mg F

# Youd probably add in a safety factor of at least 2x

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You’d probably add in a safety factor of at least 2x, however. A 0,0, 0,0, 2 0 2 C mg F - + = 173 N 2 2 C mg F = =

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As shown in the figure below, a string is wrapped around a uniform disk of mass M = 1.2 kg and radius R =0.06 m. (The moment of inertia of a uniform disk is (1/2)MR 2 .) Attached to the disk are four low mass rods of length b =0.09 m, each with a small mass m =0.8 kg at the end. The device is originally at rest on a nearly frictionless surface. You then pull the string with a constant force F =25 N. At the instant when the center of the disk has moved a distance d =0.043 m, a length w =0.024 m of string has unwound off the disk. Example: Non-Zero Torque on System
A. Explain briefly how to go solve for the motion of the device’s center of mass. How the CofM moves can be predicted by analyzing the corresponding point-particle system. Specifically, consider the net external force as acting on the device and the effect it has on K trans . Since distances are given instead of time intervals, we may calculate work more easily than impulse. So, it may be simpler to use the energy principle instead of the momentum principle. Example: Non-Zero Torque on System

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B. At the later instant, what is the speed of the devices CofM? Example: Non-Zero Torque on System initial state final state Since we are interested in the motion its center of mass, focusing on the corresponding point-particle system will be productive.
Q3. Which of these equations correctly expresses the energy priniciple applied to our point-particle system? A. K rot + K trans = F(w+d) B. K rot = Fw C. K rot + K trans = Fd D. K trans = Fw E. K trans = Fd

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B. At the later instant, what is the speed of the device’s CofM? Energy principle applied to the point-particle system corresponding to the real disk+rods system: sys E W Q = + rest trans cm E K F r Fd + ∆ = = arrowrightnosp arrowrightnosp i 2 , 1 2 total cm f m v Fd = , 2 4 cm f Fd v M m = + , , trans f trans i K K Fd - = , trans f K Fd = v << c Example: Non-Zero Torque on System
C. What is the moment of inertia of the device?

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