please show all your work. finna learn Name: 4. A 0.75kg disk has a radius of 0.
ID: 2032072 • Letter: P
Question
please show all your work. finna learn
Name: 4. A 0.75kg disk has a radius of 0.20m. It is initially rotating with an angular velocity of 5 rad's about the same axis of rotation described by the figure in question # 2, A second disk (mass-0.50kg, radius :0.30m) is placed directly above the first disk and is dropped on the first disk and the system reaches equilibrium. The disks are rough (p 0.20) Find: O rad/s a) the initial angular momentum of the system u 5 rad/s b) the final angular velocity of the system c) if the system reaches equilibrium in 0.20s, determine the average torque on the dropped disk. d) What caused this torque?Explanation / Answer
a)
initial momentum = I1?1 = 1/2 mr^2 x 5 = 0.5 x 0.75 x 0.2^2 x 5 = 0.075 kg-m^2
b)
conservation of angular mometum ,
I1 ?1 + I2 ?2 = ( I1 + I2 )
0.075 + 0 = ( 1 /2 x 0.75 x 0.2^2 + 1 /2 x 0.5 x 0.3^2 ) ?
0.075 = 0.0375 ?
? = 2 rad/s
c)
? = change in angular moemtum / t
? = final ang momeutm - initial ang mometum / t ;
? = [ ( I1 )? - ( I1?1 ) ] / 0.2
? = [ ( 0.015 ) 2 - ( 0.015 x 5 ) ] / 0.2
? = 0.225 N-m
d)
the friction caused the torque , there was some firction between the disks , muk = 0.2
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