m = mass of the athlete = 80 kg
h = height from where the athlete drops = 1.5 meters
g = acceleration due to gravity = 9.8 m/s²
v = speed with which the athlete hit the ground = ?
as per conservation of energy , the sum of potential energy and kinetic energy remain same all the time. if one increase , the other decrease by same amount to keep the total energy same.
hence in this case , as the athlete drops , the potential energy decrease due to decrease in the height. to keep the total energy constant , the kinetic energy increase by same amount.
hence ,
kinetic energy gained = potential energy lost
(0.5) m v² = mgh
dividing both side by mass "m"
(0.5) v² = gh
(0.5) v² = (9.8 x 1.5)
v = 5.42 m/s
