Work Done
We do many things like we do study for a very long period and when our study is completed we think that we have done a lot of work but according to the science we have done no work so let's get started so work is done when the force is applied on object so force must be applied and the object should be displaced due to the Force applied on it So, lets understand it with a example a boy to call stone and create now due to this process force is applied on it and you to force displacement is also done work is also done now we know what is work so now we will learn how to find the value of work ??
I want to tell you that both force and displacement have directions so now we will let there is an object on which a constant force F is acting and due to it S displacement is done then work done will be
W = F × S
Here W means work F means force and S means displacement.To find work done just multiply Force by displacement
But please note : the displacement is done in the direction of force And there is no direction of work done as it is a scalar quantity.
Unit of work is N.M because the unit of force is newton and unit of displacement is a man in the case of work neuter and displacement is multiplied and we get and autumn the unit of work is also called as you hear one julian's 1 newton forces applied on an object and it is displaced 1m
Now let us take an example to understand it !
5N Force is applied on the object And due to this it is displaced 2m Then what is the work done ??
Displacement = 2m
Force = 5N
Work Done = F×S
Work Done = 5×2
Work Done = 10 J
How to find Force ?
In exams sometime you will be given mass in the place of force and acceleration in place of displacement so in this case we can use this formula
F = ma
In which cases work is positive , negative and zero
Case 1 : when the direction of both force and displacement is same then the work will be in positive. For example when the tyre get punctucre we have to push the car here both displacement and force are in the same direction so the work is in positive '+'
Case 2 : when the direction of the displacement is opposite to the direction of force then the work done is negative ' - '
Example: Frictional Force
Case 3 : a) if forces not applied or displacement is zero than work done will be zero
b) if force is perpendicular to the displacement than work done will be zero
Here is an example for your practice !
Question: find minimum work required to lift a 15 kg bag to the height of 2 m ?
Answer : Please Do it Yourself !
Sun is the biggest source of energy Now, what is energy according to the science So an object having capability to do work is said to be possess energy SI unit of energy is Joule Kilo Joule is the bigger unit of Energy Where 1 kilo Joule = 1000 J
Types of Energy
Kinetic Energy :- kinetic energy energy possed by an object due to it's motion It's derivation
V^2-U^2=2as
S = v^2 - u^2 / 2a
Change in K.E = Work Done
How ?? Is any object is in motion then it also has kinetic energy so, Let the kinetic energy is changed then the the difference in the old kinetic energy and new kinetic energy is equal to the work done it can also written as
Final kinetic energy - Initial K.E
= Work Done
W = ½ mv^2-½ mu^2
W= ½ m (v^2-u^2)
Potential Energy :- the potential energy possessed by an object is the energy present in it by virtue of its position
P.E = mgh
Law of conservation of Energy
According to the law of conservation of energy. Energy can neither be created nor be destroyed it can only be transferred from one form to another form the total energy before and after the transformation will remain same.