Momentum *** Inertia

kgruber

kgruber

Final Approach
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Will somebody please explain these terms to me. I seem to use them interchangeably.

Thanks
Karl
 
kgruber said:
Will somebody please explain these terms to me. I seem to use them interchangeably.

Thanks
Karl
Click to expand...

In classical mechanics, linear momentum or translational momentum (pl. momenta; SI unit kg•m/s, or, equivalently, N•s) is the product of the mass and velocity of an object:
676dc21daca293b822638428a5ea3c2e.png
Like velocity, linear momentum is a vector quantity, possessing a direction as well as a magnitude.

Inertia is the resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion.

In common usage the term "inertia" may refer to an object's "amount of resistance to change in velocity" (which is quantified by its mass), or sometimes to its momentum, depending on the context. The term "inertia" is more properly understood as shorthand for "the principle of inertia" as described by Newton in his First Law of Motion; that an object not subject to any net external force moves at a constant velocity. Thus an object will continue moving at its current velocity until some force causes its speed or direction to change.

momentum is the product of inertia (m) and velocity (v). p=ma.
 
Momentum is the mass of an object times its speed. Or in mathematical form p = m*v. So something has to be moving to have momentum. A force is required to change an objects momentum.

Intertia is (sort of) an object's resistance to change in momentum. An object at rest will resist acceleration, and an object in motion will resist acceleration (to speed up or slow down). For linear motion the inertia is the mass of the object.
 
For dummies like me, my professor explained:

If large, heavy object has no velocity, it has no momentum. But it still has inertia (it'll take a big push to get it moving).
So, momentum is a function of mass and velocity. Inertia is a function of mass alone.

At least that's what I remember, take it at face value.
 
murphey said:
In classical mechanics, linear momentum or translational momentum (pl. momenta; SI unit kg•m/s, or, equivalently, N•s) is the product of the mass and velocity of an object:
676dc21daca293b822638428a5ea3c2e.png
Like velocity, linear momentum is a vector quantity, possessing a direction as well as a magnitude.

Inertia is the resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion.

In common usage the term "inertia" may refer to an object's "amount of resistance to change in velocity" (which is quantified by its mass), or sometimes to its momentum, depending on the context. The term "inertia" is more properly understood as shorthand for "the principle of inertia" as described by Newton in his First Law of Motion; that an object not subject to any net external force moves at a constant velocity. Thus an object will continue moving at its current velocity until some force causes its speed or direction to change.

momentum is the product of inertia (m) and velocity (v). p=ma.
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Yup. She's a rocket scientist. Really! LOL!
 
A more interesting question: What causes the Inertia effect?

José
 
denverpilot said:
Yup. She's a rocket scientist. Really! LOL!
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nah - wikipedia except for the last sentence. that came from my phisicks book, Halliday & Resnick - the Gold Standard.

I like Alan's explanation better.
 
PilotAlan said:
The curvature of space-time around an object, as determined by its mass?
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Hmm... this is what causes gravity.
What causes inertia?
This is like asking what causes Newtonian Laws of Physics. Or what causes principle of conservation of energy. Or what causes electro-magnetism. At some point you write the basic laws of Physics and don't ask what causes them. Super string theory? But then what causes super string theory, etc. God?

The goal of Physics is not to understand "what causes something" but (1). to have clear mathematical formulation of laws of Nature (2) to come up with the most general formulation that would have the broadest possible application (synthesis)
 
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olasek said:
Hmm... this is what causes gravity.
What causes inertia?
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Hmmm, the more important question may be: what causes levity? We all know that levity is the opposite of gravity so it is the important topic! :D
 
Clark1961 said:
Hmmm, the more important question may be: what causes levity? We all know that levity is the opposite of gravity so it is the important topic! :D
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(*spit take once again*)

I needed this. I'm having an email battle over someone who's PO'd that I didn't send an engraved letter informing him of a monthly deadline. A deadline that's been published & posted every month for years and years.
 
murphey said:
(*spit take once again*)

I needed this. I'm having an email battle over someone who's PO'd that I didn't send an engraved letter informing him of a monthly deadline. A deadline that's been published & posted every month for years and years.
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He did not realize the gravity of the situation.:rofl:
 
olasek said:
At some point you write the basic laws of Physics and don't ask what causes them. Super string theory? But then what causes super string theory, etc. God?
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It's FM. In this case, it's PFM.
 
olasek said:
At some point you write the basic laws of Physics and don't ask what causes them. Super string theory? But then what causes super string theory, etc. God?
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The Flying Spaghetti Monster is made up of strings of delicious pasta.

Coincidence? I think not.
 
PilotAlan said:
It's FM. In this case, it's PFM.
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I said that about DME and someone wanted to correct me. Guess they don't admit that the factory puts magic smoke in all electrical devices. Regardless of how it gets in there, I know for darn sure that when the magic smoke is released, the darn thing never works again...
 
Clark1961 said:
I said that about DME and someone wanted to correct me. Guess they don't admit that the factory puts magic smoke in all electrical devices. Regardless of how it gets in there, I know for darn sure that when the magic smoke is released, the darn thing never works again...
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Sometimes it doesn't even have to let the smoke out. One of our tech-support guys had a problem many years ago. He installed a UV eraseable EPROM backward. Then he called me because it didn't work. He said he installed the EPROM, the light came on for a second, then it went off, and the unit didn't work.

Me: "The light came on?"
Him: "Yeah, the little light on the top of the EPROM".
Me: "That's NOT supposed to be a light!"

--

It was FM to him.
 
denverpilot said:
The Flying Spaghetti Monster is made up of strings of delicious pasta.

Coincidence? I think not.
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Let's keep this aviation related, please

Smoke-Angel-C-17-Globemaster.jpg


His smoky appendages are wondrous.
 
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murphey said:
nah - wikipedia except for the last sentence. that came from my phisicks book, Halliday & Resnick - the Gold Standard.

I like Alan's explanation better.
Click to expand...

You, too? Boy, that brings back some ancient memories.
 
Clark1961 said:
Hmmm, the more important question may be: what causes levity? We all know that levity is the opposite of gravity so it is the important topic! :D
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If Gravitons are gravity particles, are Levittons then Levity particles?
(maybe not, I've been to Levittown, and I wouldn't call it funny. But maybe there's an observer interaction effect there)

Or if the primary subatomic particle are Quarks, then sub-levity particles are Quips?

This may be the first quantum humor on POA..... But it's humor is relative.
 
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PilotAlan said:
This may be the first quantum humor on POA..... But it's humor is relative.
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Maybe. Of course we must remember that incest is relative. Does any theory of relativity have to consider quantum humour and incest?
 
PilotAlan said:
If Gravitons are gravity particles, are Levittons then Levity particles?
(maybe not, I've been to Levittown, and I wouldn't call it funny. But maybe there's an observer interaction effect there)

Or if the primary subatomic particle are Quarks, then sub-levity particles are Quips?

This may be the first quantum humor on POA..... But it's humor is relative.
Click to expand...

Or relativistic?
 
Clark1961 said:
Hmmm, the more important question may be: what causes levity? We all know that levity is the opposite of gravity so it is the important topic! :D
Click to expand...

Gravity can be described as the flow of the space medium into mass. Much like when you put your hand on the drain of a sink full of water or on a vacuum cleaner hose. The effect appears pulling on your hand but is actually the medium (water or air) pushing your hand down. The "gravity vacuum" is created by the mass that blocks the "pressure" from the opposite side thus creating an unbalance in force. The same space medium is responsible for the inertia effect and the constant speed of light. Just like drag and constant sound velocity in air or water. But unlike fluid mediums were F = K (dx/dt) space medium is F = K (dv/dt).

José
 
Piloto said:
Gravity can be described as the flow of the space medium into mass. Much like when you put your hand on the drain of a sink full of water or on a vacuum cleaner hose. The effect appears pulling on your hand but is actually the medium (water or air) pushing your hand down. The "gravity vacuum" is created by the mass that blocks the "pressure" from the opposite side thus creating an unbalance in force. The same space medium is responsible for the inertia effect and the constant speed of light. Just like drag and constant sound velocity in air or water. But unlike fluid mediums were F = K (dx/dt) space medium is F = K (dv/dt).

José
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Fine...where's the levity? :)
 
Clark1961 said:
Fine...where's the levity? :)
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Is levity were to exist how would you keep things together. If gravity force were switched to levity (antigravity) this planet would be desintegrated. The closest effect to antigravity observed is that of a nuclear fission. In a normal state the atom nucleus is held together by the nuclear force created by protons and neutrons. When the nucleus is bombarded by a neutron the nuclear force is released and the repulsive force of the protons creates the "antigravity effect" that desintegrate the atom. The neutrons of the desintegrated atom bombard the neighboring atoms thus creating a nuclear chain reaction. Localized magnetic levitation effects has been used in trains and other applications.

José
 
Piloto said:
Is levity were to exist how would you keep things together. If gravity force were switched to levity (antigravity) this planet would be desintegrated. The closest effect to antigravity observed is that of a nuclear fission. In a normal state the atom nucleus is held together by the nuclear force created by protons and neutrons. When the nucleus is bombarded by a neutron the nuclear force is released and the repulsive force of the protons creates the "antigravity effect" that desintegrate the atom. The neutrons of the desintegrated atom bombard the neighboring atoms thus creating a nuclear chain reaction. Localized magnetic levitation effects has been used in trains and other applications.

José
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you may want to look up "binding energy" and "mass defect"
 
Piloto said:
Gravity can be described as the flow of the space medium into mass. Much like when you put your hand on the drain of a sink full of water or on a vacuum cleaner hose. The effect appears pulling on your hand but is actually the medium (water or air) pushing your hand down. The "gravity vacuum" is created by the mass that blocks the "pressure" from the opposite side thus creating an unbalance in force. The same space medium is responsible for the inertia effect and the constant speed of light. Just like drag and constant sound velocity in air or water. But unlike fluid mediums were F = K (dx/dt) space medium is F = K (dv/dt).

José
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Reads like the sci.chem trolls are here now.
 
We haven't even discussed football momentum, which can change without the application of an outside force.
 
COFlyBoy said:
We haven't even discussed football momentum, which can change without the application of an outside force.
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Or primary election momentum where money acts as a force. $3.50=1 pack of fig newton.
 
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