A helicopter has two blades (see figure), each of which has a mass of 290 kg and

Question

A helicopter has two blades (see figure), each of which has a mass of 290 kg and can be approximated as a thin rod of length 6.7 m. The blades are rotating at an angular speed of 59 rad/s. (a) What is the total moment of inertia of the two blades about the axis of rotation? (a) Determine the rotational kinetic energy of the spinning blades. Could you also please show all of the steps leading up to the answers in parts A & B? here is a picture to help: http://edugen.wileyplus.com/edugen/courses/crs6407/art/qb/qu/c09/ch08_12.gif

Explanation / Answer

Part A)

The moment of inertia of a long thin rod rotating around its end is I = 1/3ML2

Since we have two of them, the total Moment of Inertia is...

2/3(290)(6.7)2

I = 8679 kgm/s

Part B)

KE = .5I2

KE = (.5)(8679)(59)2

KE = 1.51 X 107 J

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