In which one of the following situations is there a decrease in gravitational potential energy?
The correct answer and explanation is:
Correct Answer:
A decrease in gravitational potential energy occurs when an object is lowered or falls to a lower height.
Explanation:
Gravitational potential energy (GPE) is the energy stored in an object due to its position in a gravitational field, usually relative to the Earth’s surface. The formula used to calculate GPE is:
GPE = m × g × h
Where:
- m is the mass of the object (in kilograms),
- g is the acceleration due to gravity (approximately 9.8 m/s² on Earth),
- h is the height of the object above a reference point (in meters).
A decrease in gravitational potential energy happens when the height (h) of the object decreases. This could occur if an object falls, slides down a slope, or is deliberately lowered to a lower elevation. Because potential energy is directly proportional to height, any drop in height reduces the total gravitational potential energy.
For example, if a rock is sitting at the top of a hill and then rolls down, it is losing height, and thus its gravitational potential energy is decreasing. This lost potential energy is often transformed into kinetic energy (energy of motion) as the object moves downward, or it might be transformed into other forms like sound or heat, depending on the situation.
This principle is important in physics and engineering, especially in analyzing systems involving motion and energy conservation. It also plays a role in everyday phenomena like waterfalls, roller coasters, or lifting and dropping objects. The energy transformation follows the law of conservation of energy: energy is not destroyed but changes from one form to another. When gravitational potential energy decreases, it always results in an increase in another form of energy.