- #1

gcombina

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During the time a compact disc (CD) accelerates from rest to a constant rotational speed of 477 rev/min, it rotates through an angular displacement of 0.250 rev. What is the angular acceleration of the CD?

(a) 358 rad/s2 (c) 901 rad/s2 (e) 794 rad/s2

(b) 126 rad/s2 (d) 866 rad/s2

This is my formula from my Kinetics formula in my book where ∂ = angular acceleration

(1)Kinetics formula

V^2 = V(initial)^2 + 2ax

(2)so I converted to:

ω^2 = ω(initial)^2 + 2∂θ

(477 rev/mins)^2 = (0 rad/s)^2 + 2(∂)(0.250 rev)

[(477 rev/mins)^2 - (0 rad/s)^2)]/ (2 (0.250 rev))= ∂

[(477 rev/mins)^2 - 0] / (.50 rev) = ∂

(477 rev/mins)^2 / .50 rev = ∂

(227529 rev^2/mins^2) / .50 rev = ∂

455,058 rev/mins^2 = ∂

**** I can not get the answer! the Answer is "e" ****