Answer:
306.12m
Step-by-step explanation:
Gravitational Potential Energy or GPE can be computed by the formula:
PEgrav= mgh
where:
PEgrav = GPE (J or kg.m²/s²)
m = mass (kg)
g = acceleration due to gravity (m/s²)
h = height (m)
So all you need to do is fill in what you know and solve what you don't know.
In this case the following are given:
m = 5kg
g = 9.8 m/s²
h = ?
PEgrav = 15,000J or 15,000kg.m²/s²
15,000 kg.m²/s = (5kg)(9.8m/s²)(h)

The answer is then 306.12m