An 80kg athlete jumps up 1.5 meters. with what velocity does he hit the ground ?

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

cant without the picture! ?