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 possessed by a car, moving at a speed of 5 m/sec is 5000 J. The mass of the car is
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Right Option : A | |||
View Explanation |
Two bullets P and Q, masses 10g and 20g, are moving in the same direction towards a target with velocities of 20 m/s and 10 m/s respectively. Which one of the bullets will pierce a greater distance through the target ? | |||
Right Option : A | |||
View Explanation |
The kinetic energy of a body will becomes eight times if - | |||
Right Option : C | |||
View Explanation |
Third consective year,my ward is in Abhyas with nice experience of admin and transport support.Educational standard of the institute recumbent at satisfactory level. One thing would live to bring in notice that last year study books was distributed after half of the session was over,though study ...
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Usually we see institutes offering objective based learning which usually causes a lag behind in subjective examinations which is the pattern followed by schools. I think it is really a work of planning to make us students grab the advantages of modes of examination, Objective Subjective and Onli...
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Abhyas institute is one of the best coaching institute in the vicinity of Ambala Cantt area. The teachers of the institute are well experienced and very helpful in solving the problems of the students.The good thing of the institute is that it is providing extra classes for the students who are w...
Abhyas Methodology is very good. It is based on according to student and each child manages accordingly to its properly. Methodology has improved the abilities of students to shine them in future.
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