Mastering Physics: UP517-MP itemview?assignmentProblemID 75108685 https//session
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Question
Mastering Physics: UP517-MP itemview?assignmentProblemID 75108685 https//session.masteringphysi University Physics at FDU signed in as brianna thomas Help UPS11.MP1 Problem 12.50 r previous l 3 of 7 l next Problem 12.50 Part A What is its rotational kinetic energy? A 320 g ball and a 560 g ball are connected by a 50.0 cm-long massless, rigid rod. The structure Express your answer with the appropriate units. rotates about its center of mass at 110 rpm. Value UN its Submit My Answers Give Up Incorrect: Try Again: 3 attempts remaining ContinueExplanation / Answer
KEr = ½I²
= 110 rev/min (2 rad/rev) / 60 s/min
= 11.52 rad/s
The two balls can probably be modeled as point masses where
I = mr²
the rod has no mass so contributes no moment of inertia to the problem
The center of mass is needed
320(0) + 560(50.0) = (320+560)R
R = 31.82 cm from the smaller mass
r = 50-31.82 = 18.18cm
r = 18.18 cm from the larger mass
KEr = ½(Mr²)² + ½(mR²)²
KEr = ½(Mr² + mR²)²
KEr = ½(0.560(0.1818²) + 0.320(0.3182²)11.52²
KEr = 3.38 J