Purchase Solution

Rotational inertia and kinetic energy of spinning blades

Not what you're looking for?

Ask Custom Question

A helicopter has 3 blades, each of them are 5.20m long and has a mass of 220kg.(each blade has a mass of 220kg, not the sum of the 3) The rotor is rotating at 385 rev/min.

a)What is the rotational inertia of the rotor assembly about the axis of rotation? (Each blade can be considered to be a thin rod rotated about one
end.) ____kg*m^2

b)What is the total kinetic energy of rotation?___MJ

Purchase this Solution
Solution Summary

This solution contains a brief step-by-step guide to calculate the rotational inertia and kinetic energy. The formula for the rotational inertia of a rigid rod is stated but not derived.

Solution Preview

The rotational interia of an object, such as a helicopter blade, is a measure of that object's resistance to angular accelerations -- it serves the same function as mass in the rotational analogue of Newton's law (F = ma for linear motion, F = TI for rotational motion).
<br>
<br>Rotational ...

Purchase this Solution
Free BrainMass Quizzes
Intro to the Physics Waves

Some short-answer questions involving the basic vocabulary of string, sound, and water waves.

The Moon

Test your knowledge of moon phases and movement.

Basic Physics

This quiz will test your knowledge about basic Physics.

Classical Mechanics

This quiz is designed to test and improve your knowledge on Classical Mechanics.

Introduction to Nanotechnology/Nanomaterials

This quiz is for any area of science. Test yourself to see what knowledge of nanotechnology you have. This content will also make you familiar with basic concepts of nanotechnology.

View More Free Quizzes
Related BrainMass Solutions

  • Determining Inertia and Rotational Kinetic Energy

    (a) What is the total moment of inertia of the two blades about the axis of rotation? (b) Determine the rotational kinetic energy of the spinning blades. Hello and thank you for posting your question to Brainmass!

  • Rotational kinetic energy and spring

    Each of the two wheels of the moped has a radius of 0.2 m and a moment of inertia of 0.2 kg.m2. What is the total rotational kinetic energy of the wheels? 26.

  • Skater's Final Angular Velocity

    An ice skater starts spinning at the rate of 1.5rev/s with arms extended. she then pulls her arms close to her body, resulting in a decrease of her rotational inertia to three-quarters of her initial value.

  • Angular acceleration and rotational kinetic energy

    If the blades can be approximated as uniform thin rods that rotate about one end, what is the total rotational kinetic energy of the five blades? A 50-kg rider on a moped of mass 75 kg is traveling with a speed of 20 m/s.

  • Rotational motion

    214621 Rotational motion and kinetic energy lost PROBLEM 2: A playground whirl consists of a uniform disk of mass 10M and radius R. It is spinning at a rate of 2.0 rmp. A child mass M, originally at rest, steps on to the whirl.

  • Moment of Inertia of Two Particles Located in the X-Y Plane

    To see the connection, let us find the kinetic energy of each particle. Using the formula for kinetic energy of a moving particle , find the kinetic energy of particle a and the kinetic energy of particle b.

  • Moment of Inertia of a Rotating Body

    Rotational kinetic energy = ½ Iω^2 Using this definition of Moment of Inertia lets derive a general expression for the Moment of Inertia of any object.

  • Rotational Inertia Problem

    53169 Rotational Inertia Problem A uniform solid sphere of mass 5 kg and radius of 30 cm is rotating about an axis through its center at a rate of 180 rev/min. Find the kinetic energy of the sphere. The rotational inertia of the sphere is 2/d MR^2.

  • Kinetic energy of a sphere

    116769 Finding the knetic energy of a sphere Consider a sphere of radius R and mass M rolling without slipping. Which form of kinetic energy is larger, translational or rotational? Translational kinetic energy is larger.

View More Related Solutions