(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

An airplane propeller is 2.02 m in length (from tip to tip) with mass 127 kg and is rotating at 2300 rpm about an axis through its center. You can model the propeller as a slender rod.

a)What is its rotational kinetic energy?

b)Suppose that, due to weight constraints, you had to reduce the propeller's mass to 75.0\% of its original mass, but you still needed to keep the same size and kinetic energy. What would its angular speed have to be, in rpm?

2. Relevant equations

K=0.5 (mr^2) w^2

(m***,radius,wangular speed)

3. The attempt at a solution

a)

2300 RPM = 38.33 RPS = 76.66 radians/s

2300RPM=240 rad/s

KE=0.5 (127) (1.01)^2 (240)^2 = 3731117.76 J

b)

new mass = 95.25kg

KE = 0.5(95.25)(1.01)^2 (w)^2

2 KE /(95.25)(1.01)^2) = (w)^2

[2 KE /(95.25)(1.01)^2)]^0.5 = w

but im sure my original KE is wrong so..

thanks for the help

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# Homework Help: Rotational Kinetic Energy of an airplane propeller

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