Name: A Perfect Guide to Power and Energy
Uploaded: 2019-07-19
Duration: 8 min 57 s
Description: This video explained power and any relationship between energy and power. To know all the concepts related to power and energy is explained here in this video.

Question

State the law of conservation of energy by giving suitable examples.

Accepted Answer

According to the law of conservation of energy, the total energy of the universe is conserved which also means that the total energy of an isolated system remains constant. The energy can not be created and also can not be destroyed. It can simply be converted from one type to another. The modified law of conservation of energy states that the total mass and energy of the universe is conserved.

Example: Let us consider a pendulum suspended at $C$ . Let $A$ and $B$ be the extreme positions of this pendulum and $O$ be its mean position as shown in the figure.

At the position $B$ , the bob comes to rest for a moment and its energy is entirely potential.
Therefore, potential energy at $B$ is
$U = m g h$
Here, $h$ is the height of point $B$ above point $O$ . Since the bob is at rest at $B$ , therefore, its
kinetic energy at $B$ is $K E = 0$ .

As the bob moves from $B t o O$ its potential energy changes into kinetic energy. If $v$ is the velocity at point $O$ then kinetic energy at point $O$ is
$K E = \frac{1}{2} m v^{2}$
From the above two equations we find that
$m g h = \frac{1}{2} m v^{2}$ , i.e., the potential energy at $B$ has been converted into the kinetic energy at $O$ . This proves the law of conservation of mechanical energy.

State the law of conservation of energy by giving suitable examples.

Important Questions on Energy

Learn and Prepare for any exam you want !