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# Solved: An airplane propeller is 2.08 m in length (from

ISBN: 9780321675460 31

## Solution for problem 36E Chapter 9

University Physics | 13th Edition

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Problem 36E

An airplane propeller is 2.08 m in length (from tip to tip) with mass 117 kg and is rotating at 2400 rpm (rev/min) 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?

Step-by-Step Solution:

Solution 36E Introduction We have to calculate the moment of inertia of the propeller and then we can calculate the kinetic energy. If the mass of the propeller is decreased, the moment of inertia will also decreased, hence we have to increase the rotational speed to have same kinetic energy. Here we have to calculate the increase in rotational speed. Step 1 The moment of inertia of rod about an axis passing through the center of the rod is given by, Here we have m = 117 kg and L = 2.08 m. Hence the moment of inertia is given by Step 2 The kinetic energy of a rotating object is given by Here = 2400 rpm=400 rev/s= 40 × 2 rad/s Hence the kinetic energy of the propeller is 2.66 × 10 J.

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##### ISBN: 9780321675460

This textbook survival guide was created for the textbook: University Physics, edition: 13. Since the solution to 36E from 9 chapter was answered, more than 588 students have viewed the full step-by-step answer. University Physics was written by and is associated to the ISBN: 9780321675460. The answer to “An airplane propeller is 2.08 m in length (from tip to tip) with mass 117 kg and is rotating at 2400 rpm (rev/min) 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?” is broken down into a number of easy to follow steps, and 87 words. This full solution covers the following key subjects: its, mass, propeller, rpm, tip. This expansive textbook survival guide covers 26 chapters, and 2929 solutions. The full step-by-step solution to problem: 36E from chapter: 9 was answered by , our top Physics solution expert on 05/06/17, 06:07PM.

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