An object possesses kinetic energy when it is in motion. It is defined as the amount of work that should be done to accelerate a body of a given mass from rest to a certain velocity. As this energy is gained during its acceleration, the body retains this kinetic energy till its speed is varied. While coming back to the state of rest, the same amount of energy is required by the body.
If we will calculate the kinetic energy of a non-rotating object having mass m and traveling with a certain speed v is ½ mv2 in classical mechanics. If the speed of the body is very less in comparison with the speed of light then relative mechanics is followed. The standard unit of kinetic energy is the joule, while the English unit of it is foot-pound. The kinetic energy equation is written as
K.E. = ½ mv2
Where
Mass of the body = m
The velocity with which the body is traveling = v and
The kinetic energy is articulated in kgm2/s2.
The kinetic energy formula is used to compute the mass, velocity, or kinetic energy of the body if any of the two numerics are given.
To Understand How The Kinetic Energy is Measured Based Upon The Given Details, We Can Study The Following Simple Examples
Example 1
A man is carrying a trolley of 6 kg mass with kinetic energy of 40 J. Calculate the velocity of it.
Solution
Given
Mass m = 6 kg
Kinetic energy K.E. = 40 J
Velocity v = 2 K.E./m
= 2 x 40 J/6 kg
= 13.33
= 3.65 m/s
The man is running with a velocity of 3.65 m/s.
Example 2
A car has a mass of 250 kg and is driven at a velocity of 10 m/s. Calculate its kinetic energy.
Solution
Given,
Mass of the body m = 250 kg
Velocity v = 10 m/s
The kinetic energy formula is given by
K.E. = ½ mv2
K.E. = ½ x 250 kg(10 m/s)2
K.E. = 12500 kg2s2.
The dimensional formula of kinetic energy can be given by
[M1L2T-2]
Where M = mass
L = Length
T = Time
It can be derived as follows
Kinetic energy K.E. = [Mass x Velocity2] x 2-1 ….. (1)
The dimensional formula of mass = [M1L0T0] ….(2)
Since, Velocity = Distance x Time-1 = [L] x [T]-1
Hence, the dimensional formula of velocity = [M0L1T-1] … (3)
Putting the values of equation (2) and (3) in equation (1) we will get,
Kinetic energy = [Mass x Velocity2] x 2-1
or KE = [M1L0T0] x [M0L1T-1] = [M1L2T-2].
Therefore, the kinetic energy is dimensionally represented as [M1L2T-2]
Conclusion
Kinetic energy can be transformed into other forms of energy and is transferred between objects. To accelerate an object we need to apply force and to apply force we need to do work. When work is done the energy is transferred to the other object and it starts moving.