Not enough information - you need to know the mass of the flagstone. The idea is to use the formula for gravitational potential energy:
GPE = mgh
(The product of mass, gravity, and height). The mass should be in kilograms; gravity is about 9.8 newtons/kilogram.
"rock"
The higher above the ground an object is, the greater its potential energy.
The potential energy of a 12.1 kg mass 17.1 m above the ground is 2,027.72 joules.
The potential energy of a 0.480kg bird sitting 22.8m above the ground is 107.25 joules.
The potential energy of a body of 1.0 kg mass 1.0 m above ground is 9.8 joules.
The potential energy, expressed in joules, is 196 times its height above ground, expressed in meters.
The higher above the ground an object is, the greater its potential energy.
Potential Energy
The potential energy of a 0.480kg bird sitting 22.8m above the ground is 107.25 joules.
The potential energy of a 12.1 kg mass 17.1 m above the ground is 2,027.72 joules.
The potential energy of a body of 1.0 kg mass 1.0 m above ground is 9.8 joules.
Potential
The potential energy, expressed in joules, is 196 times its height above ground, expressed in meters.
The potential energy of a 0.480kg bird sitting 22.8m above the ground is 107.25 joules
potential energy it is directly proportional to height of object above ground
Potential Energy
If using the formula U=mgh, then potential energy increases when the height above the ground increases.
When an object is at a position above the ground, it has gravitational potential energy. This is so because of the force of gravity that tends to pull objects to the ground.