Wikipedia:Reference desk/Archives/Science/2023 January 18

= January 18 =

Which equations are being used here?
I recently saw an 8-video playlist applying physics to analyze several different Pokémon. These videos usually show all the important equations onscreen, and I was able to follow through with and corroborate the results of the video creator (for the first and third videos, I got different results for a few things due to assuming values for certain variables that are different than the values assumed by the video creator). The exception is with this sixth video, in which I cannot determine a lot of the equations being used starting at the 3:07 mark (excluding the use of the Pythagorean theorem on the horizontal and vertical velocity to get the diagonal velocity and the inverse trigonometry to get the jumping angle, though I don’t know how he got the vertical velocity). Primal Groudon (talk) 01:32, 18 January 2023 (UTC)
 * The vertical acceleration of a body in free fall is given by dv/dt = −g. Since this is constant during free fall, we may replace this by Δv/Δt = −g, so Δv = −gΔt = −9.8&thinsp;m/s2&thinsp;×&thinsp;11.2&thinsp;s = −109.76&thinsp;m/s. I have not followed the rest in detail, but suppose it uses the conservation of energy Ekin&thinsp;+&thinsp;Epot = 1/2&thinsp;mv2&thinsp;+&thinsp;mgh, so Δ(v2) = −2gΔh. --Lambiam 08:30, 18 January 2023 (UTC)    (Added note:) Somewhat confusingly, the variable named "v" in the first set of equations stands for the magnitude of only the vertical component of the velocity, while in the final two equations it denotes the magnitude of the full velocity.  --Lambiam 20:14, 19 January 2023 (UTC).


 * Wikipedia has an article called "kinematics." "Kinematics" is also the name for these kinds of equations - the "geometry of motion," as described in the article.  Nimur (talk) 16:59, 19 January 2023 (UTC)