A 2.0 kg, 20cm-diameter turntable rotates at 100 rpm on

Lorraine Harvey

Lorraine Harvey

Answered question

2022-01-06

A 2.0 kg, 20cm-diameter turntable rotates at 100 rpm on frictionless bearings. Two 500 g blocks fall from above, hit the turntable simultaneously at opposite ends of a diameter, and stick. What is the turntable’s angular velocity, in rpm, just after this event?

Answer & Explanation

abonirali59

abonirali59

Beginner2022-01-07Added 35 answers

The mas of turntable M=2Kg
Diameter of the turntable d=20cm=0.2m
Angular velocity ω=10r±=100×2π60=10.47rads
Mass of the two blocks m=500g=0.5kg
To determine the turntable's angular velocity once the two blocks stick with it. When the two blocks collide, the moment of inertia of the entire system changes, causing the angular velocity of the system to change. The angular velocity of the turntable can be calculated using conservation of angular momentum:
Litial=Lfal
Iturntabω=Iblockω+Iturntableω+Iblock2ω
ωw angular velocity
ω=IturntableωIblockω+Iturntableω+Iblock2ω
Iturntable=Mr22=2×0.122=0.01
Iblock1=mr20.5×0.12=0.005=Iblock2
ω=0.01×10.470.005+0.01+0.005
=5.235rads
=5.235×602π=50r±

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