Expression for Kinetic Energy
Expression for Kinetic Energy
Kinetic Energy: The energy of an object because of its motion is called its kinetic energy. Its SI unit is Joule (J). A flying bird, a running man, a moving train and a swinging bat are some examples of bodies with kinetic energy. Kinetic energy of a body moving with certain velocity is equal to the work done on it to make it acquire that velocity. Kinetic energy of an object increases with its speed.
· Due to kinetic energy, a bullet fired from a gun can pierce a target.
· A moving hammer, drives a nail into a wooden block. Due to its motion, it has kinetic energy or ability to do work.
The kinetic energy of a body of mass m moving with a velocity v is
Sometimes, a large rock from space hits the earth’s surface at a very high speed. Its huge kinetic energy creates a large crater on the earth’s surface. One such crater was formed thousands of years ago at Lonar in Maharashtra. The diameter of this crater is 1.8 km.
Expression for Kinetic Energy: Suppose a body of mass “m” moving with a uniform velocity “u”. Force “F” starts acting on it in the horizontal direction and displaces it through a distance of “s” and it attains a velocity “v”. Then, work done to increases its velocity from “u” to “v”.
According to equation of motion:
So, as the object starts from rest and distance travelled is x
(1)
According to the definition of Force
F = ma
Or
Putting the value of a in the Equation (1), we get
But Fx is the work done by the force on the body. It should be equal to the increase in the kinetic energy of the body as it moves from A to B. Also, since the kinetic energy at A was zero, the increase in kinetic energy should be equal to the kinetic energy at B. So, we conclude the following:
The kinetic energy of a body of mass m moving with a speed v is
Example:Find the kinetic energy of a ball of mass 200 g moving at a speed of 20 cm/s.
Solution The kinetic energy is
Given m= 200g = 0.2 Kg
v = 20 cm/s = 0.2m/s
Q. If a stone of mass 3 kg be thrown with a kinetic energy of 37.5 J, find its velocity.
Solution: Here, mass m = 3 kg, K.E. = 37.5 J, velosity of stone, v = ?
From
Kinetic energy of a body moving with speed 10 m/s is 30J. If its speed becomes 30 m/s , its kinetic energy will be ______________- | |||
| Right Option : D | |||
| View Explanation | |||
Kinetic energy possessed by a car, moving at a speed of 5 m/sec is 5000 J. The mass of the car is
| |||
| Right Option : A | |||
| View Explanation | |||
An object P of mass 2 kg is moving at 10 m/sec and object Q of mass 3 kg is moving at 7 m/sec. Which object will possess more K.E.? | |||
| Right Option : A | |||
| View Explanation | |||
Students / Parents Reviews [20]
A marvelous experience with Abhyas. I am glad to share that my ward has achieved more than enough at the Ambala ABHYAS centre. Years have passed on and more and more he has gained. May the centre flourish and develop day by day by the grace of God.
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Barkha Arora
10thIn terms of methodology I want to say that institute provides expert guidence and results oriented monitering supplements by requsite study material along with regular tests which help the students to improve their education skills.The techniques of providing education helps the students to asses...
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8thI have spent a wonderful time in Abhyas academy. It has made my reasoning more apt, English more stronger and Maths an interesting subject for me. It has given me a habbit of self studying
