The amount of gravitational potential energy acquired by the rock is equal to:
[tex]\Delta U = mg \Delta h[/tex]
where
m is the mass of the rock
g is the gravitational acceleration
[tex]\Delta h[/tex] is the increase in height of the rock
Substituting the data of the problem, we find
[tex]\Delta U=(15 kg)(9.81 m/s^2)(1.5 m)=220.7 J[/tex]
So, Natalie gave 220.7 J of energy to the rock.
