Answer:
h = 10 m
Step-by-step explanation:
As per energy conservation law we know that if there is no friction force present in the system then in that case total energy is always remains conserved.
So here we can say that
initial potential energy = final kinetic energy

here we know that
m = 0.25 kg
v = 14 m/s
now from above equation


so initial vertical height will be h = 10 m