How high will a 1.85 kg rock go if thrown straight up by someone who expends 80.0 J of energy on it?

Answer 1

Kinetic energy at ground = 80

Kinetic energy at max height = 0
so
Potential energy at max height = 80
so
m g h = 80

h = 80/(1.85*9.81)

Answer 2

Kinetic energy at ground = 80

Kinetic energy at max height = 0
so
Potential energy at max height = 80
so
m g h = 80

h = 80/(1.85*9.81)