Angular Momentum 

marhabaan

his name is Mr. Andersen

obviously not, *effective

And now we know how to apply the word _effective_ in a sentence. Hooray. Ironically, the comment meant to contradict anonymous's opinion gave another argument as to why it is correct. Ah... the youtube comment section...

>implying this video is about grammar

anonymous clark haha....noope!

you mastermind jesus, do you live by the play hamilton? Ah yes

He's the man.

no

S. You mean hank green's brother???

NERD

backdraftvideos photos

nah sig figs

yeah the calculations to get the velocity isnt shown so we can rely that sig figs round to 11

true he must have made a mistake but his explanations were so clear

You're thinking of tau = r cross F, which is how we define torque. L= sum(r cross p) is angular momentum's definition from linear momentum.

Im not an expert but the direction can mean tension or compression on a rotating shaft for example. look at the guy rotating on the chair, on a clockwise rotaion the forces are oposite ( this is a tensile force) on the other case it would be compression on the rotating shaft. i hope it helps

The subject area of ‘Angular Momentum’ seemed to me, filled with lots of miss understandings and miss interpretations. The Rotary Motion as a whole in the world, starting from the child’s Top, bicycle and to end up with solar systems and galaxies, have not been explained acceptably enough. Many different demonstrations are there to be observed but the phenomenon is not explained well. However teachers got used to defend themselves by referring of the matter to the gloomy theorem of “Conservation of Angular Momentum” which cannot be understood by human beings. I am not afraid to challenge this theory of ‘Conservation of Angular Momentum’ because it doesn’t have any provable mathematical, practical or logical basis behind. From my childhood I was against of the ‘direction of angular momentum’. Why hand rules if the mechanism behind the phenomenon is clear to the founder? Just for an argument’s sake, you can imagine a child who is rotating a mass tied by a thread around his finger. It is clear that the rotating object possesses a certain angular momentum. At once the thread is broken and the mass is thrown away in a straight line. Then what is the ‘Conservation of Angular Momentum’ there? But ‘Energy’ is conserved there, after and before the incident as well. Therefore Albert Einstein’s ‘Conservation of Energy’ is adequate to explain every energy based dynamics in the universe and other kinds of conservations are not logically acceptable. The fault is with the society for accepting the entire package produced by the great scientist Sir Isaac Newton without testing or challenging over centuries. There is no argument that Newton is the greatest among all the practical scientists ever lived upon Earth. But a certain part of a theory could be erroneous and it is the fault of other scientists who lived ever since without testing the contents to identify erroneous sections. Therefore the scientists of the 21st century have the soul responsibility to challenge and test the Himalayan stock of unfiltered knowledge base ever accumulated through centuries in the field of Physical Science or unless our prospective kids will certainly go mad by mental pollution. Theories must be frequently challenged or unless ‘Physics’ too would become a conservative subject such as ‘History’ or ‘Archeology’. Paradoxes are always manmade and products by wrong theorizations. ‘Reality’ itself is simple enough to understand by a man, or unless it cannot be the ‘Reality’ The theory of ‘Action & Perpendicular Reaction’ can explain all the complicated cases related to rotary systems. (The theory is first published as ‘The Alternative Dimension in Angular Momentum’ /Space Dynamics-V4/2012 and this can be considered as the second edition of the previous publication.)

i'm so confuse on the formula of point object. so what's the purpose of the first formula L=r x p and the second one L= r x m v?

@@rafsanbinhossain9261 the video tells you this. They are how you calculate the angular momentum of either a rotating item (like a ball on the end of a string) or a revolving object (like a pushbike wheel)

@@EarlJohn61 dm

NERD

Yes. Angular momentum doesn't necessarily have anything to do with magnetism. It is a measure of the distribution of linear momentum, based on how far it is from a reference point, that has analogous properties with linear momentum. Moment in general means quantity multiplied by distance from a reference point, which will apply for magnetic and electric dipole moments. There is a connection between angular momentum and magnetic dipole moments at the quantum level, where the property of electrons known as spin, is what gives ferromagnetic materials their magnetic behavior. It is very complicated how quantum spin relates to any actual spin, so most instructors try to tell you "it is just a name" and dismiss your follow up question to understand why it has that name or what exactly is spin (the question every student has at one point). This is a common thing that happens with terms in quantum mechanics, because we assign names to quantum concepts, with very complicated connections to how it relates to that name in normal terms. Another example being color charge, that has nothing to do with the visible color of matter.

Angular momentum is "Geek Talk" for circular rotation.

Mahira Gulzar Radians are not "real" units. We use them as a reminder that we are using radians to begin with.

Assuming it is uniform, solid, and cylindrical, yes.

the law of conservation of momentum. by changing the direction of the wheel, you change the angular momentum, because of the law of conservation there is another momentum created by the chair to keep the total momentum the same

The torque that the person is applying to the handles of the wheel's axis.

p is linear momentum. It is equal to m*v. So instead of writing p in the second formula he writes it out to m*v.

He takes average.

Star Messenger dude. u serious? research before u talk shit. I learnt this Right and Left HR in the 10th grade

Radians are a dimensionless quantity, so we "get to" do that. Radians refer to a ratio of arc length to radius, both of which have units of meters. Since everyone brought meters to the party, we cancel the units. We commonly specify radians when it is an angle or angular kinematics quantity, just to remind us what the term is.

As there is no external torque, angular momentum is conserve and by rotating the wheel axis he is introducing new angular momentum into the system which makes wheel rotating itself in other direction producing angular momentum of same magnitude thus total angular momentum remain conserve. It's what I think.

Due to its association with tangential velocity

Maybe L=τ x r=τ*r*sinθ(cross multiply). So, the L should be perpendicular to the rotation. I think it is not important, it is just for people to calculate the vector L easily.

The radian is a dimensionless unit. It is a ratio of arc length to radius.

btw the earth turns/rotates on its axis AND orbits other bodies of gravitational masses