# How to find kinetic energy

The energy possessed by a body by virtue of its motion called the kinetic energy. Explanations of kinetic energy and ways to find kinetic energy are discussed here. Click here to know more about the kinetic energy.

# How to find kinetic energy

### “The energy possessed by a body by virtue of its motion called the kinetic energy”

Every object in the universe has kinetic energy to move from one place to another. The energy possessed by a body by virtue of its motion called the kinetic energy.  A rocket travelling to the Moon has kinetic energy as does a snail crawling along a wall. It is the kinetic energy of objects that makes them difficult to stop and the kinetic energy of the air in a hurricane that causes severe damage to the countryside.

• Mass of the object(m)
• Speed or velocity (v)

In general the work done on an object is equal to the change in the kinetic energy of the object. If the final speed v is greater than the initial speed u then W is the work done in accelerating the object over a distance s. If the final speed v is less than the initial speed u then W is the work done in slowing the object down over a distance .

### Kinetic energy Definition:

• Kinetic energy is one of many types of energy that exist. This is energy generated because something is moving — the faster it’s going, the more kinetic energy it has. A person sitting has no kinetic energy, but a person running like a maniac has tremendous kinetic energy:

• The energy possessed by a body because of its motion, equal to one half the mass of the body times the square of its speed.

• The amount of kinetic energy KE of an object in translational motion is equal to one-half the product of its mass m and the square of its velocity v.

• Kinetic energy is given as follows,

Kinetic energy = ½(mv2)

• The greater the mass and/or the speed of a moving object, the greater its Kinetic Energy.

### Formula to find Kinetic energy

All moving objects have kinetic energy. The kinetic energy an object has depends on its:

• Mass

• Speed

The equation for calculating kinetic energy:

KE = ½ mv2

or

KE = ½ × m × v2

• KE = the kinetic energy in joules, J

• m = the mass in kilograms, kg

• v = the speed in metres per second, m/s

### Example problem to find kinetic energy

A herder is herding his sheep into the kraal. A mother sheep and its lamb are both running at 2,7 m·s−1 towards the kraal. The sheep has a mass of 80 kg and the lamb has a mass of 25 kg. Calculate the kinetic energy for each of the sheep and the lamb

### Solution

Given data:

Velocity or speed of mother sheep and lamp, v =2.7 m·s−1

Mass of the mother sheep = 80 kg

Mass of the lamb = 25 kg

To find:

• kinetic energy of mother sheep

• kinetic energy of lamb

Formula:

Kinetic energy of the object = ½*mv2

Calculation:

• kinetic energy of mother sheep

K.E =1/2*(80)*(2.7)2

= 2916 Joules

• kinetic energy of lamb

K.E =1/2*(25)*(2.7)2

= 1913 Joules

### Note:

Even though the sheep and the lamb are running at the same velocity, due to their different masses, they have different amounts of kinetic energy. The sheep has more than the lamb because it has a higher mass.