Explain each of the following questions.
( a) Can an object– Earth system have kinetic energy and not gravitational potential energy?
( b) Can it have gravitational potential energy and not kinetic energy?
( c) Can it have both types of energy at the same moment?
( d) Can it have neither?
(a) To determine whether an object-Earth system can have kinetic energy and not gravitational potential energy, we need to understand the definitions of these energy types.
1. Kinetic energy is the energy that an object possesses due to its motion. It depends on the mass of the object and its velocity. The formula for kinetic energy is KE = 0.5 * mass * velocity^2.
2. Gravitational potential energy is the energy an object possesses due to its position in a gravitational field. It depends on the height of the object from a reference point and its mass. The formula for gravitational potential energy is GPE = mass * gravity * height.
Considering these definitions, we can conclude that an object-Earth system can have kinetic energy without having gravitational potential energy. This situation occurs when the object is in motion but is at a height where the gravitational potential energy is low or zero. For example, if an object is moving horizontally along the ground, it has kinetic energy but negligible (or zero) gravitational potential energy.
(b) Similarly, we need to understand the definitions to determine if an object-Earth system can have gravitational potential energy without having kinetic energy.
An object-Earth system can have gravitational potential energy without having kinetic energy if the object is stationary at a certain height in a gravitational field. In this case, the object has potential energy due to its position in the field, but since it is not in motion, it does not possess kinetic energy. So, the answer is yes, it is possible for an object-Earth system to have gravitational potential energy without having kinetic energy.
(c) Now, let's consider whether an object-Earth system can have both kinetic energy and gravitational potential energy at the same moment.
Yes, it is possible for an object-Earth system to have both types of energy simultaneously. For example, when an object is thrown upwards, it initially has kinetic energy due to its motion. As it moves upward against the Earth's gravitational field, it slows down, and its kinetic energy decreases. At the same time, its height increases, leading to an increase in gravitational potential energy. So, during the upward motion, the object possesses both kinetic energy and gravitational potential energy.
(d) Finally, let's explore the possibility of an object-Earth system having neither kinetic energy nor gravitational potential energy.
In order for an object-Earth system to have neither kinetic energy nor gravitational potential energy, the object must be at rest (not moving) and at a height where the gravitational potential energy is zero or negligible. Additionally, the object must not possess any other form of energy, such as thermal or chemical energy. So, it is theoretically possible for an object-Earth system to have neither kinetic energy nor gravitational potential energy, but it is a highly specific scenario that would require appropriate conditions.