Consider a rigid body that is rotating. Which of the following is an accurate st

Question

Consider a rigid body that is rotating. Which of the following is an accurate statement? a) Its center of rotation must be moving with a constant velocity. b) All points on the body are moving with the same linear velocity. c) All points on the body are moving with the same angular velocity. d) Its center of rotation is its center of gravity. A turntable was revolving at 33 1/3 rpm. It was shut off and uniformly slowed down and stopped in 5.5 seconds. A) What was the angular acceleration? a) -0.8 rad/sec^2 b) 5.6 rad/sec^2 c) -0.63 rad/sec^2 d) 9.8 rad/sec^2 B) Through how many revolutions did it turn? a) 2.5 rev b) 1.5 rev. e) 5.6 rev d) 10 rev

Explanation / Answer

22 ans

basing on radius is equal at any point of object the body always moving at constant angular velocity

so the correct option is C

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23 ans

Given that

angular speed W=33.3 rpm=3.5 rad/sec

time t=5.5 sec

now we find the angular acceleration

the angular acceleration =0-3.5/5.5=-0.63 rad/sec^2

now we find the how many revolutions it rotates

W=2*3.14*n/t

3.5=2*3.14*n/5.5

number of revolutions n=3/2=1.5 rev

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