Final answer:
The potential energy of a water tank with a mass of 38,000 kg on a 58 m high building is 21,563,880 joules, calculated using the formula PE = mgh, where g is 9.81 m/s², the acceleration due to gravity.
Step-by-step explanation:
To calculate the potential energy of the water tank on the roof of an apartment building, we use the formula PE = mgh, where PE stands for potential energy in joules (J), m is the mass in kilograms (kg), g is the acceleration due to gravity which is approximately 9.81 m/s² on Earth's surface, and h is the height in meters (m).
For the brick example, the calculation would be PE = 1 kg × 9.81 m/s² × 4 m, which gives us a potential energy of 39.24 J at the top of the roof. Once the brick has fallen to the ground, its potential energy is 0 J since the height is now 0 m.
In the case of the water tank with a mass of 38,000 kilograms at a height of 58 meters, the potential energy can be calculated by substituting the given values into the formula: PE = 38,000 kg × 9.81 m/s² × 58 m, which equals 21,563,880 J.