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yaseen shah
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does Newtons first law discribes Newtons third law.
Yes, 3rd law essentially describes the "resistance" attributed to inertia, but there is no connection to 1st law there. 1st law doesn't say that body resists motion. It says that whenever you try to change the way it moves, you have to apply force.yaseen shah said:My friends i think first law that describes about inertia that Inertia is property of a body by virtue of it resists motion but in the form of force that he exerts equal on that body which apply force.
In my opinion 3rd law describes quantitative behavior of inertia.
DaleSpam said:For example, the forces could act in the same direction.
Or the accelerations could be equal instead of the forces.
Or the Lagrangian could depend on position.
Just keep this in mind.The Lagrangian is terribly unintuitive to me.
K^2 said:Just keep this in mind.
[tex]F_q = \frac{\partial L}{\partial q}[/tex]
The Newton's 2nd in terms of this Fq is also relatively easy to write down.
[tex]\frac{d}{dt}p_q = F_q[/tex]
It's exactly the same as classical Newton's F=ma, except written with generalized momentum. And of course, it's easy to find the actual generalized momentum.
[tex]p_q = \frac{\partial L}{\partial \dot{q} }[/tex]
Naturally, substituting this momentum into Newton's 2nd gives you a very familiar result.
[tex]\frac{d}{dt} \frac{\partial L}{\partial \dot{q}} - \frac{\partial L}{\partial q} = 0[/tex]
And that's all there is to it.
Yes, such a universe would not look like ours at all. A head on collision between a fly and a train would be as disastrous for the train as the fly. I don't know if extended objects could even form.Pythagorean said:Ok, that ones kind of mind-melting to think about assuming mass conservation still holds. I watch a ball fly by me and hit a fence that is stationary with respect to me. Once the ball and the fence contact, their instantaneous accelerations would have to somehow match up, so one would have to jump to the other or something, and the forces would bend around the will of the acceleration law.
K^2 said:Well, the actual definition is Σpq-H. That way, you can build L even when you aren't sure exactly which energies are which. As long as you can write total energy in terms of generalized coordinates, you can define it. And don't try to think of it as a physical quantity. Just think of it as a generator for generalized forces and generalized momenta.
DaleSpam said:Yes, such a universe would not look like ours at all. A head on collision between a fly and a train would be as disastrous for the train as the fly. I don't know if extended objects could even form.
But the point is that such a universe could be consistent with Newton's 1st law, despite not being consistent with the 3rd law. They are not redundant.
K^2 said:First law holds in an inertial coordinate system. Third law holds in any coordinate system.
This is a good point, and already a kind of hint for the need of GR and tensors etc.K^2 said:if you fix the first law by introducing fictitious forces, you end up breaking the 3rd law
The relationship between Newton's First and Third Laws is that they are both part of Newton's three laws of motion. The First Law states that an object will remain at rest or in motion with a constant velocity unless acted upon by an external force. The Third Law states that for every action, there is an equal and opposite reaction. These two laws work together to explain the behavior of objects in motion.
Yes, a common example is when a person is standing on a skateboard. According to Newton's First Law, the person will remain at rest unless acted upon by an external force. When the person pushes off the ground with their foot, they are exerting a force in one direction (action). This causes the skateboard to move in the opposite direction (reaction), as stated by Newton's Third Law.
Understanding the relationship between these two laws is crucial in understanding the behavior of objects in motion. It helps explain why objects move the way they do and how forces act upon them. This knowledge is essential in fields such as physics, engineering, and even everyday life.
Yes, there are exceptions to both Newton's First and Third Laws. The First Law does not apply to objects in space, as they are not affected by external forces. The Third Law does not apply to non-contact forces, such as gravity, which do not have an equal and opposite reaction.
Newton's First and Third Laws have had a significant impact on modern science and technology. They have allowed for the development of various inventions, such as airplanes, cars, and rockets, by understanding the relationship between forces and motion. These laws have also formed the basis for more complex theories, such as Einstein's theory of relativity.