science 9th work and energy in 9th std
Answers
1. Work : In physics work is defined if force applied on object displaces the object in direcetion of force. all three terms force, displacement and direction of force are important W= Force x displacement (force in direction of displacement)
Unit of work
1 Joule = 1 Newton. 1 metre
1 J= 1 Nm
2.Energy : The energy may be defined as the capacity of a body to do work.
The SI unit of energy is joule (J).
or 1 kJ = 1000 J
Answer:
1. work = work is said to be done when a force applied on an object cause displacement of the object.
work = force × displacement
2. 1 joule = If a force of 1 Newton displays an object through 1 metre in the direction of the force, the amount of work done on the object is 1 joule. Therefore 1 joule = 1 Newton × 1 metre
1J = 1N × 1m
3.Positive = when the force and displacement are in the same direction the work done by force is positive.
4.Negative = When the force and displacement are in opposite direction the work done by force is negative.
5.Zero = when the force applied does not cause any displacement or when the force and the displacement are perpendicular to each other then the work done by the force is zero.
6.Energy = the capacity of body to perform work is called its energy.
The SI unit system is Joule and CGS system is erg.
7. Kinetic energy = the energy which an object has because of its motion it's called its kinetic energy.
kinetic energy is = work done on the object.
K.E = F×s
8. Potential energy = the energy stored in an object because of its specific state or position is called potential energy.
P.E = mgh
9. Law of conservation of energy :- energy can neither be created nor destroyed it can be converted from one form to into another thus the total amount of energy in the universe remain constant.
10. Power = power is the rate at which work is done.
power = work / time.
P = W / t.
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