Final answer:
The gravitational potential energy of a 4kg ball 1m above the ground is 40 joules, calculated using the formula G.P.E. = mgh.
Step-by-step explanation:
To calculate the gravitational potential energy (G.P.E.) of an object on Earth, you can use the formula G.P.E. = mgh, where m is the mass in kilograms, g is the acceleration due to gravity (approximately 10 m/s² on Earth), and h is the height in meters. For the example of a 4kg ball 1m above the floor, we would calculate it as follows: G.P.E. = 4kg × 10 m/s² × 1m = 40 joules.
In the scenario given for reference, a 1 kg brick on a 4 m high roof would have a gravitational potential energy of 40 joules at the top (G.P.E. = 1kg × 10 m/s² × 4m). Once the brick falls to the ground, its gravitational potential energy becomes zero because its height above the ground is zero.