/sci/ - Science & Math » Thread #12654706

103KiB, 1280x720, simple.jpg

View Same Google iqdb SauceNAO

Anonymous Tue 02 Feb 01:47:00 2021 No.12654706 View Reply Original Report

Quoted By: >>12654718

The only force acting on a ball is gravity. The ball is falling downward.
In a perfect world, the time derivative of energy is zero since energy is conserved. If PE + KE = E then the time derivative of energy is a positive number according to pic related because the time derivative of v is g and the time derivative of h should be v. Energy is constantly increasing over time. Am I retarded?

Anonymous

Anonymous Tue 02 Feb 2021 01:54:11 No.12654717 Report

Quoted By: >>12654726

Yes, retard, kinetic energy would keep increasing as long as the constant force of gravity exists. That's what a constant force is. Until it hits the ground, the amount of energy increases quadratically.

Anonymous

Anonymous Tue 02 Feb 2021 01:55:19 No.12654718 Report

Quoted By: >>12654739

>>12654706
Total mechanical energy is conserved.

$E_{tot} = m\left(\frac{1}{2}v^2 + gh\right)\\<br />\frac{dE_{tot}}{dt} = m\left(\frac{1}{2}2v\frac{dv}{dt} + g\frac{dh}{dt}\right) \\<br />\frac{dE_{tot}}{dt} = m\left(vg -gv\right) = 0<br />$

No contradictions. You need a negative sign when taking the derivative with respect to height because height is decreasing.

Anonymous

Anonymous Tue 02 Feb 2021 01:58:17 No.12654726 Report

Quoted By: >>12655359 >>12655393

>>12654717
>energy is created by falling
try again

Anonymous

Anonymous Tue 02 Feb 2021 02:02:30 No.12654739 Report

Quoted By: >>12654763 >>12655966

>>12654718
If velocity is in the negative direction, isn't it technically decreasing?

Anonymous

Anonymous Tue 02 Feb 2021 02:09:55 No.12654763 Report

Quoted By:

>>12654739
Formally, kinetic energy is actually a dot product.

$KE = \frac{1}{2}m (\vec{v}\cdot\vec{v})$

When you take the derivative with the dot product, you recognize that

$\vec{v} < 0 \\<br />\frac{d\vec{v}}{dt} < 0 \\$

So this suggests

$\frac{dKE}{dt} > 0$

As expected.

Anonymous

Anonymous Tue 02 Feb 2021 06:38:44 No.12655359 Report

Quoted By: >>12655966

>>12654726
kinetic energy, retard. he's right

Anonymous

Anonymous Tue 02 Feb 2021 06:53:39 No.12655393 Report

Quoted By:

>>12654726
https://en.wikipedia.org/wiki/Watermill

are you retarded?

Anonymous

Anonymous Tue 02 Feb 2021 11:21:55 No.12655966 Report

Quoted By:

>>12655359
his point is (i think) that energy is not “created”, just the constant mechanical energy converting from potential to kinetic
>>12654739
yes

Capcode	All Only User Posts Only Moderator Posts Only Admin Posts Only Developer Posts
Show Posts	All Only With Images Only Without Images
Deleted Posts	All Only Deleted Posts Only Non-Deleted Posts
Ghost Posts	All Only Ghost Posts Only Non-Ghost Posts
Post Type	All Only Sticky Threads Only Opening Posts Only Reply Posts
Results	All Grouped By Threads
Order	Latest Posts First Oldest Posts First

Your latest searches