Imagine holding a mic at a height above the ground. It is released and falls toward the ground.
Ignoring air resistance or friction, which of the following must be true?
a
Before it falls, all of its energy must be potential energy
b
At the end of its fall, all of its energy must be converted to kinetic energy
c
During its fall, the combination of its kinetic and potential energy must equal the amount of potential energy with which it started
d
Total energy = Kinetic Energy + Potential Energy
e
All of the above
e. All of the above.
The correct answer is (e) All of the above.
When holding the mic at a height above the ground, it possesses potential energy due to its position relative to the ground. As it falls, this potential energy is converted into kinetic energy, which is the energy of motion. At the end of its fall, all of its energy is in the form of kinetic energy.
During its fall, the combination of its kinetic and potential energy must equal the amount of potential energy it had initially. This is because energy is conserved in the absence of external forces like air resistance or friction.
The total energy of the mic, which includes both kinetic energy and potential energy, is constant throughout the fall. Therefore, the equation Total energy = Kinetic Energy + Potential Energy holds true.
To determine which of the options is true, we need to understand the concept of energy conservation. In a scenario where there is no air resistance or friction, the total energy of the system stays constant throughout the fall.
Let's break down each option to see which one is true:
a) Before it falls, all of its energy must be potential energy: This statement is not true. When the mic is held at a height above the ground, it has both potential energy (due to its position) and kinetic energy (due to its motion in the hand).
b) At the end of its fall, all of its energy must be converted to kinetic energy: This statement is not true. At the end of the fall when the mic hits the ground, it will lose all its potential energy but acquire an equal amount of kinetic energy.
c) During its fall, the combination of its kinetic and potential energy must equal the amount of potential energy with which it started: This statement is not true. During the fall, the potential energy reduces as the mic gets closer to the ground. At the same time, the kinetic energy increases.
d) Total energy = Kinetic Energy + Potential Energy: This statement is true. In this scenario, the total energy (the sum of kinetic energy and potential energy) remains constant throughout the fall. Energy is conserved.
e) All of the above: This option is incorrect because options a, b, and c are not all true. Only option d, "Total energy = Kinetic Energy + Potential Energy," is correct.
Therefore, the correct answer is option d.