Height of baby carriage from ground = 21m
Mass of carriage with baby = 1.5 kg
The carriage has potential energy by virtue of its height.
Potential energy = mgh = 1.5×10×21 = 315 J
Hence, potential energy of the carriage is 315 Joule.
Maybe this would help understand it better.
<span>Tectonic plates can transport both continental crust and oceanic crust, or they may be made of only one kind of crust. Oceanic crust is denser than continental crust. At a subduction zone, the oceanic crust usually sinks into the mantle beneath lighter continental crust</span>
The Law of the Conservation of Energy is stating that the total mechanical energy is always conserved or in simpler terms, not used or saved.