Bikash T. Magar • 21 Reads • Pdf

Rotational Mechanics is all about applying Newton's Law from the rotational frame of reference.

A flat uniform disk of radius 2R has a hole of radius R removed from the center. The resulting annulus is then cut in half along the diameter. The remaining shape has mass M. What is the moment of inertia of this shape, about the axis of rotational symmetry of the original disk?

What is the purpose of the spin cycle of a washing machine? Explain in terms of acceleration components.

How might you determine experimentally the moment of inertia of an irregularly shaped body about a given axis?

In western astrology, there are 12 astrological ages corresponding to 12 zodiac signs. The completion of these 12 ages takes about 25,920 years. Knowing that as astrology stemmed from observational astronomy, can you guess what could be the origin of the cycle where the apparent position of the sun relative to the backdrop of the stars at some seasonally fixed time slowly regresses?

To maximize the moment of Inertia of a flywheel while minimizing its weight, what shape and distribution of mass should it have? Explain.

An Olympic high diver starts his dive with a double somersault while keeping his arms neatly tucked to his chest. But as he approaches the pool surfaces, his arms stretch over his head to a point and his entire body becomes streamlined during the impact with the water. What is the reason for his routine?

Why it is necessary to use shoulder straps and a lap belt in a car while a lap belt is sufficient in a plane, even though a plane moves much faster than a car?

A yo-yo falls to the bottom of its cord and then climbs back up. (a) Does it reverse its direction of rotation at the bottom? Explain your answer.

(b) What "pulls" the yo-yo back to the top?

In cutting down a tree, a logger makes a cut on the side facing the direction in which the tree is to fall. Explain why. Would it be safe to stand directly behind the tree on the opposite side of the fall?

A student stands on a table rotating with an angular speed while holding two equal dumbbells at arm's length. He pulls his hands towards him, what's its consequence? But now, without moving anything else, the two dumbbells are dropped to the floor. What change, if any, is there in the student's angular speed? Is angular momentum conserved?

An arrow turns in flight so as to be tangent to its flight path at all times. However, a football (thrown with considerable spin about its long axis) does not do this. Why this difference in behavior?

Why it is much more difficult to balance yourself on a bicycle that is at rest than on one that is rolling?

Why does a long bar help a tightrope walker to keep his or her balance?

You are walking along a narrow rail and you start to lose your balance. If your start falling to the right, which way do you turn your body to regain balance? Explain

A helicopter flies off, its propellers rotating. Why doesn't the body of the helicopter rotate in the opposite direction?

Explain in terms of angular momentum and rotational inertia, exactly how one "pumps up" a swing in the sitting position.

There are no MCQs in Mattrab Library for this chapter yet.