Explain about Work, Energy and Power

Work, Energy and Power

What is work?

When force is applied on any object and object tends to move is called work done. there is displacement of the object or body. it is a scalar quantity

The amount of work is equal to the product of applied force and displacement of body in the direction of force. it is written as

Work done = Force × Displacement W = F.d SI Unit of Work – Joule CGS unit of Work – Erg [ 1 Joule = 107 erg ] Note – 1. Amount of work done by the force is 0 if there is no displacement. 2. amount of w.d. by the force is 0 displacement is normal to the direction of force.

Explain about energy it’s type and unit?

It is the capacity of body to do work. When work is done by the body energy is decreases and when the work is done on the energy is increases.

Units of Energy:-

• SI unit – Joule
• CGS Unit – Erg
• Commercial unit – KWh

Types of Energy:-

There are two types of energy:

1. Potential Energy
2. Kinetic energy

1. Potential energy : When the body have energy by virtue of its position it is known as potential energy of the body. it is expressed by the equation given below

P.E. = mgh where m = mass of the body h = height of the body is lifted g = acceleration due to gravity

2. Kinetic Energy : When the body is in the motion it possessed some energy it is called kinetic energy. it expressed by the formula

K.E. = 1/2 mv²

where v=velocity of the body

Conservation of Energy:-

According to law of conservation of energy “energy can neither be created nor be destroyed; it can only be converted from one form to another form. it means that total energy in a closed system is constant.

Instrument	Transformation of energy
Solar cell	Light energy into Electrical energy
Microphone	Sound energy into electrical energy
Loudspeaker	Electrical energy into sound energy
Musical instrument	Mechanical energy into sound energy
Heater	Electrical energy into thermal energy
Bulb/Tube	Electrical energy into light energy
Electric cell	Chemical energy into electrical energy

Power and it’s unit:

It is rate of doing work. mainly it depends on 2 factors: work done and time taken to do work. it is written as

P=W.D./Time

SI unit of Power: Watt or Joule/sec or horse power (hp) [1hp=746watt]

CGS unit of power: erg/s

Frequently Asked Questions:

 

1. KWh is the unit of ?

A) Work
B) Power
C) Energy
D) Acceleration

ANSWER= (C) Energy
Explain:-
Check Answer

 

2. Energy in relevance to time is related to

A) Force
B) Power
C) Work
D) Efficiency

ANSWER= (B) Power
Explain:-
Check Answer

 

3. SI unit of Power is:

A) N-m
B) Newton
C) Watt
D) Dyne

ANSWER= (C) Watt
Explain:-
Check Answer

 

4. one watt is equal to:

A) J/s
B) J/m
C) N-m
D) None of these

ANSWER= (A) J/s
Explain:-
Check Answer

 

5. Two quantities that have same SI unit are:

A) Work and Energy
B) Work and Force
C) Work and efficiency
D) Energy and Power

ANSWER= (A) Work and Energy
Explain:-
Check Answer

 

6. SI unit of Energy is:

A) Watt
B) Newton
C) Joule
D) Pascal

ANSWER= (C) Joule
Explain:-
Check Answer

 

7. Energy used by a moving object is termed as:

A) Kinetic Energy
B) Potential energy
C) Thermal Energy
D) All of the Above

ANSWER= (A) Kinetic Energy
Explain:-
Check Answer

 

8. Formula for Kinetic energy is:

A) MV^2
B) Ma^2
C) 1/2M^2V
D) 1/2MV^2

ANSWER= (D) 1/2MV^2
Explain:-
Check Answer

 

9. Formula for work done is:

A) F+s
B) F-s
C) F/s
D) F×s

ANSWER= (D) F×s, where F is force and s is displacement
Explain:-
Check Answer

 

10. Power is defined as:

A) P = W/d
B) P = d/W
C) p = W/t
D) P = t/W

ANSWER= (C) p = W/t, where W is work and t is time
Explain:-
Check Answer

Read Also-

• Fundamental quantities and its units
• Force, its types and its units
• Motion and it’s type
• Pressure and it’s Unit
• Surface Tension and it’s applications
• Explanations of elasticity and Hooke’s law
• Heat transfer and Modes of heat transfer

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Work, Energy and Power