Final answer:
The gravitational potential energy of a bell weighing 25 kg at the top of a 45 m tower is 11017.25 joules. Similarly, a 1 kg brick at the top of a 4 m roof has a potential energy of 39.24 joules, which is reduced to 0 joules when it is on the ground.
Step-by-step explanation:
To calculate the potential energy of an object due to its position in a gravitational field, the formula PE = mgh is used, where PE is the potential energy in joules (J), m is the mass in kilograms (kg), g is the acceleration due to gravity (9.81 m/s² on Earth), and h is the height in meters (m). For the bell in the question, with a mass of 25 kg and at a height of 45 m, the potential energy can be calculated as follows:
PE = mgh
PE = (25 kg) × (9.81 m/s²) × (45 m)
PE = 11017.25 J
Therefore, the gravitational potential energy of the bell is 11017.25 joules.
Using a similar approach, the potential energy of a 1 kg brick at a height of 4 m can be calculated:
PE = mgh
PE = (1 kg) × (9.81 m/s²) × (4 m)
PE = 39.24 J
When the brick is on the ground, its potential energy is 0 J, as potential energy is relative to the height from which it can fall.