Conservation of Angular Momentum
المؤلف:
Professor John W. Norbury
المصدر:
ELEMENTARY MECHANICS & THERMODYNAMICS
الجزء والصفحة:
p 149
29-12-2016
2486
Conservation of Angular Momentum
For translational motion we had
and for 
we had 
= constant, i.e. conservation of momentum. Similarly from 
, then if there are no external torques 
then the total angular momentum is conserved, namely
Example A student is spinning on a stool and holding two heavy weights with outstretched hands. If the student brings the weights closer inward, show that the spin rate increases.
Solution For a rigid body spinning about a fixed axis we had 
. Angular momentum is conserved, thus
or
The moment of inertia of the two weights is I = 2Mr2 where r is the length of the student's arm. The rotational inertia of the student remains the same. Thus
giving
And ri > rf giving 
.
MASTER TABLE
الاكثر قراءة في الميكانيك
اخر الاخبار
اخبار العتبة العباسية المقدسة
