21. An antique phonograph rotates at 33 1/3rpm. a) find its angular velocity in
ID: 2025102 • Letter: 2
Question
21. An antique phonograph rotates at 33 1/3rpm.a) find its angular velocity in rad/s
b)find the speed of a point 5cm from the center
c) if the record starts from rest and accelerates with a constant angular acceleration to 33 1/3rpm in 2s, find the angular acceleration and the angle turned through, in degrees and revolutions
d) if the phonograph shuts off and the player decelerates uniformly from 33 1/3 to a stop in 2 complete revolutions, find the angular acceleration and the time it takes to come to a stop
Explanation / Answer
(a). Angular velocity = 33 1/3 rpm = 33 1/3 *2 rad / 60 s = 3.49 rad / s (b).Distance r = 5 cm = 0.05 m So, required speed v = r = 0.174 m / s (c).Initial angular speed ' = 0 Angular speed after 2 s is = 33 1/3 rpm = 3.49 rad / s Time t = 2 s Angular accleration = ( -') / t = 1.745 rad /s 2 Angular displacment = 't + ( 1/ 2) t 2 = 0 + 3.49 = 3.49 rad = 3.49 /2 rev = 0.555 rev We know 1 rev = 360 degrees So, = 0.555 * 360 degrees = 199.96 degrees ~ 200 degrees (d). Initial velocity = 33 1/3 rpm = 3.49 rad / s Final velocity " = 0 Angular displacement ' = 2 rev = 2x 2 rad = 12.566 rad from the relation " 2 - 2 = 2'' Angular accleration ' = [" 2 - 2 ]/ 2' = -0.4846 rad / s 2 Required time t ' = ( " - ) / ' = 7.201 s Required time t ' = ( " - ) / ' = 7.201 sRelated Questions
Hire Me For All Your Tutoring Needs
Integrity-first tutoring: clear explanations, guidance, and feedback.
Drop an Email at
drjack9650@gmail.com
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.