Answer:
Velocity = 20.3 [m/s]
Step-by-step explanation:
This is a typical problem of energy conservation, where potential energy is converted to kinetic energy. We must first find the potential energy. In this way, we will choose as a reference point or point where the potential energy is zero when the carrriage rolls down 21 [m] from the top of the hill.
Now this will be the same energy transformed into kinetic energy, therefore: