I seems to be an paradox when working with energy. If a person going 20 m/s to 40 m/s the kinetical energy gain is (40^2-20^2)/2= 600 J. Now imagine that i goinng in the opposite diraction with speed 10 m/s. Now the kinetical energy gain of the person is (50^2-30^2)/2=800 J. I see this as an Paradox? Maybe not, just an effect of two different moving reference frame...
The energy of a moving object is $E = mv^2\;.$ That is it increases with velocity squared.  I walk at say 3 miles per hour, or lets round that down to 1 meter per second for a slow walk. I weigh less than $100~\mathrm{kg}\;,$ but lets just round that up to $100~\mathrm{ kg}$ for convenience (it is just after Christmas).  So when I walk along the pavement, I have $100~\mathrm{kg\; m^2 s^{-2}}$, 100 joules of kinetic energy.  Now I get on a passenger jet, which is cruising at around 500 knots, call that 250 meters per second.  In my seat I have $100\times 250^2 = 6250000$ joules of kinetic energy. But when I walk down the aisle I have $100\times 251^2 = 6300100$ joules of kinetic energy. The difference between these is: 50100 joules.  It feels the same to me, walking down the pavement as walking down the aisle of the plane. I didn't have to make some huge effort to get up to speed on the plane, yet I needed 500 times the energy to do it.  How is this possible, and where did the energy come from?
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(I flagged in good faith so even if it is a genuine name declining seems harsh) So, in my physics textbook it's written that the kinetic energy possessed by a body is equal to the amount of work done by an opposing force to stop the body, now that got me thinking that when a ball hits a wall, the wall which is the opposing force does no work  because there is no displacement, so to say isn't the kinetic energy possessed by the ball zero? 18.04.01 Not available for server Change object pivot point orientation For some reason the pivot point on my object has become rotated (other objects show normally oriented pivot points). I have to set the "transformation orientation" (see the bottom of my screenshot) to be able to see it though. Does anyone know how to change it back? That is, change it to be aligned with the "world orientation". Why are my sauces splitting? Recently all my attempts at sauces are splitting and I'm not sure what's going wrong. 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