The two quantites are defined as follows:
[tex]\text{Potential Energy:}\quad E=mgh[/tex]
[tex]\text{Kinetic Energy:}\quad E=\dfrac{1}{2}mv^2[/tex]
So, a child with mass [tex]m=35[/tex]kg sits at a height [tex]h=3.5[/tex]m has potential energy
[tex]E=mgh=35\cdot 9.8\cdot 3.5=1200.5 J[/tex]
Similarly, if the same child moves with speed [tex]v=5[/tex]m/s, he has kinetic energy
[tex]E=\dfrac{1}{2}mv^2=\dfrac{1}{2}\cdot 35\cdot 25=437.5J[/tex]
