Johnny Knoxville is building up thrust with his jet ski in a pool. (The jet is first held with a rope to get full speed) then he hits a ramp to get enough gravitational energy to jump over a 2 meter high hedge. And then …. The jet crashed on the floor, Johnny folded against wheel. Luckily the energy only causes some bruises and no broken bones or teeth. If you could measure under the jet then you would notice that this (and the floor below it) has become a bit warmer. So that’s where the went….
Energy conversion: kinetic to gravitational and THUD! Ouch! heat