Kinetic Energy - Definition, Examples, Formula, FAQs

What is Kinetic Energy?

Kinetic energy is the energy possessed by a body due to its motion. Any object that is moving has kinetic energy. The amount of kinetic energy depends on the mass of the object and its speed. A fast-moving object has more kinetic energy than a slow-moving one, and a heavier object has more kinetic energy than a lighter one if both move with the same speed.

Formula of Kinetic Energy

The kinetic energy of a moving object is given by:

$
\text { Kinetic Energy }=\frac{1}{2} m v^2
$

where
$m$ = mass of the object (in kg), $v=$ velocity of the object (in m/s)

Units of Kinetic Energy

The SI unit of kinetic energy is joule (J).

$
1 \text { joule }=1 \mathrm{~kg} \mathrm{~m}^2 \mathrm{~s}^{-2}
$

Other units:

• erg (CGS system)
• electron volt (eV)

Examples of Kinetic Energy

Here are some daily-life examples of kinetic energy…

• A moving car on the road has kinetic energy.

• A rolling ball possesses kinetic energy.

• Flowing water in a river has kinetic energy.

• A flying bird has kinetic energy.

• A running person has kinetic energy.

• Wind moving the blades of a windmill has kinetic energy.

Also read -

• NCERT Solutions for Class 11 Physics
• NCERT Solutions for Class 12 Physics
• NCERT Solutions for All Subjects

How does Kinetic Energy get transferred?

Kinetic energy is a type of energy that may be exchanged between objects and turned into other forms of energy. The yo-yo is an excellent illustration of kinetic energy transformation. When you first start playing with it, you should let it rest in your hand; at this time, all of the energy is stored in the ball as potential energy. When a person drops the yo-yo, the stored energy is converted into kinetic energy or movement energy. All of the energy in the ball is transformed into kinetic energy once it reaches the bottom of the yo-yo. As it returns to the hand, all of the energy is transformed back to potential energy.

There is a ball (Image-1) that has potential energy, when we dropped the ball (Image-2) the ball started falling and now it has Kinetic Energy.

Learn kinetic Energy Better from the Given Video Below

Difference between Kinetic Energy and Potential Energy

Solved Example Based On Kinetic Energy

Example:
Find the kinetic energy of a body of mass $\mathbf{2} \mathbf{~ k g}$ moving with a velocity of $\mathbf{5 ~ m} / \mathbf{s}$.
Given:
Mass, $m=2 \mathrm{~kg}$
Velocity, $v=5 \mathrm{~m} / \mathrm{s}$

Formula:

$
\text { Kinetic Energy }=\frac{1}{2} m v^2
$

Solution:

$
\begin{gathered}
\text { K.E. }=\frac{1}{2} \times 2 \times(5)^2 \\
\text { K.E. }=1 \times 25 \\
\text { K.E. }=25 \mathrm{~J}
\end{gathered}
$