In our daily life, work is an activity that requires muscular or mental exertion. But in physics, the term has a distinctly different meaning, involving a force acting on a body while the body undergoes a displacement.
The work done by a constant F is defined as the product of the component of the force in the direction of displacement we can express work done by the force analytically as,
W=F S cos θ = F cos θ S
Where
F - represent the magnitude of the vector F
S - represent the magnitude of the vector S
θ - s angle b/w F and S
It can also be written as,
W=F S cos θ
POWER:
From the practical point of view it is interesting to know not only the work done by a force on an object but also the rate at which the work is being done.
We define power as the rate of doing work when an amount of power is done in time the average power.
WORK DONE BY VARIABLE FORCE:
The work done by variable force cannot be calculated by the direct use of formula for the entire displacement as because the formula is continuously changing with the displacement be considered here a simple case in which the force is changing only in magnitude we assume that the force is pointing in the positive direction of x-axis and the body is concentrated to move in that direction.
We can obtain an approximate value of the work done by a variable force in the following way
We divide the total displacement into a large number of small intervals each of weight a constant force is supposed to act throughout and interval this content force is taken to be the force which really act as the beginning of each of intervals obviously such a chosen constant force is different from different in intervals the work done by a force f x acting in the interval constructed at x is
W = f x ∆x
ENERGY:
Energy is the capacity of doing work energy is associated with the performance of the work because the more work that is done the greater the quantity of energy is needed work is always done by a force it means that of body possessing an energy can exert force on any other body to do work on the other hand when our done work is done on a body and equal amount of energy stored in it.
KINETIC ENERGY:
The energy possessed by a body by virtue of its motion is called Kinetic energy K.E.
i.e : ball moving can break a glass window as writing hammock and by one layer and a stone thrown upward can lift itself against the force of gravity.
To find an expression for keep of an object in motion we have to determine the work done by the moving object this is obviously equal to the change in K.E o the object
K.E = 1/2 MV.V
Energy is the most important physical concept
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