Potential energy is the stored energy of an object. While, Kinetic energy is the energy possessed by an object in motion.
Thus, for a rolling toy, the energy transformation is :
Potential Energy ⇒ Kinetic Energy
To compute for Gravitational Potential Energy:
[tex]PE= mgh[/tex]
for Kinetic Energy:
[tex]1/2mv^{2} [/tex]