Kinetic energy of anything is (1/2) (mass) (speed)² .
Your kinetic energy just before you snap back up (? ?) is
(1/2) (your mass in kilograms) (50 m/s)² =
(1/2) (your mass in kilograms) (2,500 m²/s²) =
(1,250 x your mass in kilograms) . The unit is Joules.