Download the App!

Get 24/7 study help with the Numerade app for iOS and Android! Enter your email for an invite.

(II) Suppose our Sun eventually collapses into a white dwarf, losing about half its mass in the process, and winding up with a radius 1.0$\%$ of its existing radius. Assuming the lost mass carries away no angular momentum, what would the Sun's new rotation rate be? (Take the Sun's currentperiod to be about 30 days) What would be its final kinetic energy in terms of its initial kinetic energy of today?

Get the answer to your homework problem.

Try Numerade free for 7 days

Like

Report

$5 \times 10^{-2} \mathrm{rad} / \mathrm{s}$$K_{\text {final}}=2 \times 10^{4} K_{\text {initail}}$

Physics 101 Mechanics

Chapter 11

Angular Momentum; General Rotation

Moment, Impulse, and Collisions

Rotation of Rigid Bodies

Dynamics of Rotational Motion

Equilibrium and Elasticity

Rutgers, The State University of New Jersey

University of Michigan - Ann Arbor

University of Washington

University of Sheffield

Lectures

02:21

In physics, rotational dynamics is the study of the kinematics and kinetics of rotational motion, the motion of rigid bodies, and the about axes of the body. It can be divided into the study of torque and the study of angular velocity.

04:12

In physics, potential energy is the energy possessed by a body by virtue of its position relative to others, stresses within itself, electric charge, and other factors. The unit for energy in the International System of Units is the joule (J). One joule can be defined as the work required to produce one newton of force, or one newton times one metre. Potential energy is the energy of an object. It is the energy by virtue of an object's position relative to other objects. Potential energy is associated with restoring forces such as a spring or the force of gravity. The action of stretching the spring or lifting the mass is performed by a force which works against the force field of the potential. The potential energy of an object is the energy it possesses due to its position relative to other objects. It is said to be stored in the field. For example, a book lying on a table has a large amount of potential energy (it is said to be at a high potential energy) relative to the ground, which has a much lower potential energy. The book will gain potential energy if it is lifted off the table and held above the ground. The same book has less potential energy when on the ground than it did while on the table. If the book is dropped from a height, it gains kinetic energy, but loses a larger amount of potential energy, as it is now at a lower potential energy than before it was dropped.

06:02

Suppose our Sun eventually…

03:45

04:43

(II) Suppose our Sun event…

03:54

02:33

Suppose that the Sun runs …

01:37

In a little over 5 billio…

01:24

The Sun's mass is $2.…

White dwarf A star the siz…

04:18

Suppose a uniform spherica…

01:06

Like all stars, the Sun co…

02:26

Use conservation of angula…

06:08

so here, subscript by you denotes initial on after notes final So we have the final mass to be half off The initial mass on the final duty is to be 1% off The initial radius on this is equal to 0.1 are times the initial regis now Omega I are the initial angular velocity is one revolution in 30 days on DDE Let's first converted into radiance for seconds So one revolution is basically to buy Radian on DDE In one day we have 1000 86,400 seconds. So here we have our initial angular velocity in units off Radiant for second Now since the total mass carries are we know angular momentum, the angular momentum off the remaining Mars will be same as the initial angular momentum. First we died l I be called a and F which means that the angular momentum is guns off because there is no external dark. This gives I I go toe I am a guy to be equal to i f times only life From here we can write on expression for the final angler velocity so this will be equal to initial angular velocity times the initial issue off the initial and final moment off inertia. And since the mosque is a spear, you know that moment of inertia off a spear through about its center is equal to by five times half do over five times half sorry to over five times a muskrat. So we use this expression over here, so I I is to almost five, eh? My time's all I skirt over to over five and 1/2 times r f scared so drew over five to over five guns allowed And now we ride a muff on our different arms off and I and I So this will be equally doe Omega chi times And I thought I scared your brush. Cedar 0.5 and light times Ciro Porn 01 Ali skittish. Let me. That is the final expression in the speech, so Oh, my God f But the equal door omega I dying's do. I am standing by force and this is basically solving this part off Date a question. Now we will use Omega chi the value that we found here. Oops. In this, a question on DDE they get forming a F to be equal to 4.84 age times 10 to the minus two lady in per second. And this is the value off the final angular velocity on Since Stein billiard is don't buy over only God, I'm Let's rightto by Toby nearly cool. Do six over omega. This is like approximate soon. This means that the f will be equal. Do six over. Oh, my God. And since so I think this Okay, so we might not need to simplify this. Okay, so let me just start again from here. So this from here we can ride that b i over b f is equal to Omega f over only guy. This means that the f is equal to be I dines only got eyes Allies I only got it. And omega I over Omega F is basically one over two bangs dented by four. So from here, we can say that the feedyard that would be 20,000 times smaller than the initial period and this will make it about 1 30 seconds. So, me, this job that okay about the issue off the angular, kinetic energy off the spending loss will be as follows. So we know that traditional kinetic energy is half times I only go script so K f over K I f means initial. And I saw the F men's final and I stands for initial. This will be going to do the respective Iomega scared half off Iomega Scare off boat Now begin solved. This a question? We already know what will be iii's. Physically this I will be the denominator. We know Omega Chi and Omega F You know the ratio. We can simply use the ratio two times 10 to the park for here on DDE. We get this value, Toby two times in the fourth. This means that k f physical dough You die in standard the by four off. Okay, this is what exactly record on the Q

View More Answers From This Book

Find Another Textbook