Talk:Newton's laws of motion

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— Assignment last updated by Ahlluhn (talk) 00:57, 31 May 2024 (UTC)

Semi-protected edit request on 21 July 2024

In the paragraph:

"Acceleration can likewise be defined as a limit:$$a={\frac {dv}{dt}}=\lim _{\Delta t\to 0}{\frac {v(t+\Delta t)-v(t)}{\Delta t}}.$$Consequently, the acceleration is the second derivative of position, often written ${\frac {d^{2}s}{dt^{2}}}$."

Change the equation:

${\frac {d^{2}s}{dt^{2}}}$

to:

${\frac {d^{2}p}{dt^{2}}}$

So that p matches the position variable name Traviskaufman (talk) 22:44, 21 July 2024 (UTC)

References

No, the variable for position is s. Johnjbarton (talk) 14:39, 22 July 2024 (UTC)

Inaccurate paraphrasing of newton's second law

Newton's second law is paraphrased as "At any instant of time, the net force on a body is equal to the body's acceleration multiplied by its mass or, equivalently, the rate at which the body's momentum is changing with time.". Change in momentum is only equal to mass times change in acceleration if the mass of the body is constant. It might be best to simply remove the part about acceleration times mass and rephrase it as "At any instant of time, the net force on a body is equal to the rate at which the body's momentum is changing with time." Michaelmay123 (talk) 18:28, 19 September 2024 (UTC)

It is my understanding that both statements of Newton's 2nd law are only true if the mass of the body remains constant. It is common to see Newton's 2nd law refer specifically to a particle or rigid body, rather than simply a body. The implication is that the mass of a particle or rigid body does not change with time. See Euler's laws of motion; I have added this to "See also".

When dealing with a body whose mass is changing with time, such as a rocket accelerating as the result of thrust associated with ejection of a high-speed mass of gas from a nozzle, a slightly different equation is required. Dolphin (t) 03:05, 20 September 2024 (UTC)

The "changing mass" Newton's formula is often misused, some/many would argue. Yes, it works, but the notion of a body as an entity that loses its mass by becoming more than one body is, philosophically, quite, ahm,... silly? Take for example a rubberband gun: the gun of mass M-m and a bullet of mass m are taken as two bodies (total mass M). And so should be a rocket of mass M-dm and the expelled gas of mass dm, at any instant of time. Ponor (talk) 14:39, 20 September 2024 (UTC)

" zeroeth law"

zero is not an ordinal. Fail Fail Fail Athanasius V (talk) 13:13, 22 September 2024 (UTC)

Sometimes used in physics. For example, see Zeroth law of thermodynamics. Dolphin (t) 13:19, 22 September 2024 (UTC)