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How do you change the speed without changing the angular momentum?
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What is the relation between torque and angular momentum?
Torque is the rate of change of angular momentum.
What must be exerted on an object to change the angular momentum?
A torque.
Do all objects have a momentum?
No. An object has momentum only if it is in motion..There are two kinds of momentum: linear momentum(or translational momentum), and angular momentum (or rotational momentum)..Linear momentum is a vector quantity and is calculated as mass x velocity (p = mv). Therefore, if an object's velocity is zero, then it has no linear momentum, but if an object is in motion, then it does have linear momentum..VERY IMPORTANT NOTE: Velocity, and therefore linear momentum, is always relative to the frame of reference. For a more complete discussion about velocity, see the related answer, referenced below, entitled 'How to Find Velocity'..Angular momentum is a pseudovector quantity that describes the momentum of an object that is spinning or rotating in place. An object has angular momentum only when it is spinning, or rotating about an axis. When an object is not spinning or rotating, then it does not have angular momentum..It is possible for an object to have only linear momentum, only angular momentum, or both angular and linear momentum. Note that this discussion falls apart in quantum mechanics, so we are only discussing classical physics - that is, every day observable objects, and not light particles (photons), electrons, or other quantum particles..All objects do have inertia, which is a resistance to a change in its momentum.
How does the law of conservation of momentum relate to work?
It relates to work in the sense that work involves moving things, which involves changing their momentum, and to change momentum you have to create an equal and opposite momentum so that momentum is conserved - although the planet Earth is such a convenient momentum sink that in most cases this happens without being specifically noticed.
What is one way to increase the momentum of an object?
Momentum is of two kind. One is linear momentum and the other is angular momentum. Linear momentum is defined as the product of the mass and the velocity. Hence a vector quantity. To change the momentum of a given body with its mass constant, its velocity is to be changed. Velocity change could be made by changing its magnitude or direction or both. Angular momentum is the product of moment of inertial and the angular velocity. Same manner, angular momentum is also a vector quantity as angular velocity is a vector quantity. Most of us think that moment of inertia of a body about any prescribed axis is also a vector quantity. It is totally wrong as far as my approach is concerned. Moment of inertia is a scalar quantity. So to change the momentum, some force can be applied by allowing a moving body to collide with. Angular momentum can be changed by applying torque on it. Torque colloquially saying is a turning force. Moment of effective force about an axis is termed as torque.
What is the relation between torque and angular momentum?
Torque is the rate of change of angular momentum.
The angular momentum of the earth is constant?
More or less. There is a law of conservation of angular momentum, according to which Earth can't gain or lose angular momentum on its own - if for example it loses angular momentum, it has to go somewhere. A meteor who falls into the Earth, or a rocket leaving the Earth can change Earth's angular momentum - but the total angular momentum (e.g., of the system meteor + Earth) is the same, before and after the impact.
What must be exerted on an object to change the angular momentum?
A torque.
What quantities are needed to calculate angular momentum?
"Rate of change" means that you divide something by time ("per unit time" or "per second"), so you would use the units of angular momentum, divided by seconds.I am not aware of any special name for this concept.
What are ways of changing momentum?
You change momentum by changing mass or, more commonly, velocity.
How do you cause a change in momentum?
Usually by changing the velocity.
Do all objects have a momentum?
No. An object has momentum only if it is in motion..There are two kinds of momentum: linear momentum(or translational momentum), and angular momentum (or rotational momentum)..Linear momentum is a vector quantity and is calculated as mass x velocity (p = mv). Therefore, if an object's velocity is zero, then it has no linear momentum, but if an object is in motion, then it does have linear momentum..VERY IMPORTANT NOTE: Velocity, and therefore linear momentum, is always relative to the frame of reference. For a more complete discussion about velocity, see the related answer, referenced below, entitled 'How to Find Velocity'..Angular momentum is a pseudovector quantity that describes the momentum of an object that is spinning or rotating in place. An object has angular momentum only when it is spinning, or rotating about an axis. When an object is not spinning or rotating, then it does not have angular momentum..It is possible for an object to have only linear momentum, only angular momentum, or both angular and linear momentum. Note that this discussion falls apart in quantum mechanics, so we are only discussing classical physics - that is, every day observable objects, and not light particles (photons), electrons, or other quantum particles..All objects do have inertia, which is a resistance to a change in its momentum.
How does the law of conservation of momentum relate to work?
It relates to work in the sense that work involves moving things, which involves changing their momentum, and to change momentum you have to create an equal and opposite momentum so that momentum is conserved - although the planet Earth is such a convenient momentum sink that in most cases this happens without being specifically noticed.
What idea is supported by the fact that the sun and planets rotate in the same direction on the same plane?
It's a demonstration of their angular momentum vectors being aligned in almost the same direction. Laplace added up all the vectors for the planets (the angular momentum vector is directed along the axis of rotation) and defined an invariable plane for the solar system, which is a plane that stays the same all the time. Total angular momentum is conserved so this plane will never change, even though momentum might be exchanged between the planets as their orbits change slightly.
What is one way to increase the momentum of an object?
Momentum is of two kind. One is linear momentum and the other is angular momentum. Linear momentum is defined as the product of the mass and the velocity. Hence a vector quantity. To change the momentum of a given body with its mass constant, its velocity is to be changed. Velocity change could be made by changing its magnitude or direction or both. Angular momentum is the product of moment of inertial and the angular velocity. Same manner, angular momentum is also a vector quantity as angular velocity is a vector quantity. Most of us think that moment of inertia of a body about any prescribed axis is also a vector quantity. It is totally wrong as far as my approach is concerned. Moment of inertia is a scalar quantity. So to change the momentum, some force can be applied by allowing a moving body to collide with. Angular momentum can be changed by applying torque on it. Torque colloquially saying is a turning force. Moment of effective force about an axis is termed as torque.
Conservation of angular momentum tells us?
Angular momentum will not change unless an external torque acts upon the system The short answer would be that angular momentum is conserved, i.e. it cannot be created nor destroyed. A more technical answer would be that there is a certain theorem in theoretical physics called Noether's theorem which shows that if a physical theory exhibits rotational invariance (i.e. the physics are the same even if you rotate the system) that angular momentum conservation is a result. According to particle physics therefore the conservation of angular momentum seems to tell us that the Universe is invariant under rotations. This might seem strange, because surely rotating yourself changes how think look, but the physics involved remains the same.
Why does earth rotate constantly?
Actually it doesn't - but the changes are quite small. There is a physical law called Conservation of Angular Momentum - the total angular momentum (informally, we might say the "amount of rotation") can't increase or decrease in a closed system. If the distribution of masses on Earth changes, Earth's angular velocity can change - but any redistribution of masses is rather small-scale, compared to the size of the Earth. On the other hand, Earth rotates slower and slower over time - angular momentum is transferred to the Moon in this case.
