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# The Ultimate Learning Guide

written by Stanley Udegbunam || Dec 27, 2020 ## WHAT IS KINETIC ENERGY?

Kinetic energy is the energy possessed in a body by virtue of its motion.

Kinetic energy is a scalar quantity which means it has magnitude but no direction.

## WHAT IS THE FORMULAR FOR KINETIC ENERGY?

The formula for kinetic energy is:

 K.E =  1/2 mv2

Where,

K.E is the kinetic energy of the object

m is the mass of an object

v is the velocity of an object

Hence, Kinetic energy depends on mass and velocity.

## EXAMPLES OF KINETIC ENERGY

1. A river flowing at a certain speed possesses kinetic energy.
2. A truck moving down the road at a certain speed has more kinetic energy than a car traveling at that same speed because the truck has more mass than the car.
3. A flying plane has a very high kinetic energy not only because of its large mass but also because of its high velocity.
4. Bullets from guns have high kinetic energy due to the large amount of velocity possessed by the bullet.
5. When we work, run or jog, we possess some amount of kinetic energy. a bicycle in motion possesses kinetic energy

## TYPES OF KINETIC ENERGY

• Radiant Energy: A type of kinetic energy that travels in waves through medium or space.

Examples include the Sun, the light bulb, the glowing coil on an electric cooker.

• Sound Energy: This is energy produced by the vibration of an object. Sound energy needs a medium for its propagation and travels out in all directions. They can’t travel in a vacuum. Examples include voices and musical instruments.
• Thermal Energy: This is also a type of kinetic energy that exists due to motion and collision of atoms and molecules. Example: a heated cooking spoon.
• Electrical Energy: This is energy resulting from the flow of electric charges. Examples include electric Iron, lightning.
• Mechanical Energy: This is the energy stored in objects. It is the sum of kinetic energy and potential energy. Example: A moving tricycle.

## WHAT IS THE UNIT OF KINETIC ENERGY?

The standard metric unit of measurement for kinetic energy is the Joule.

 1 Joule = 1 kg • m2/s2

## HOW TO CALCULATE KINETIC ENERGY

An object of mass 5kg is moving at a constant velocity of 15ms-1. Calculate its K.E

Solution

K.E = 1/2mv2

K.E = 1/2 × 5 × 152 = 562.5 J

1. Determine the kinetic energy of a 825-kg convertible car that is moving with a speed of 22.4 m/s.

(Tap on the option tab to reveal answer)

X wrong!!

##### b. 2.07 × 10^5 Joules

✔ Correct

2. If the convertible car in the above problem is moving with three times its speed, what would be its new kinetic energy?

X wrong!!

✔ Correct

✔ Correct

X wrong!!

## 4. A 900-kg propulsion jet moving at 30 m/s has 405,000 Joules of kinetic energy. Estimate its new kinetic energy if it is moving at 15m/s.

✔ Correct

##### b. 205,700 J

X wrong!! 