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Work, Energy and Power

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Physics Part I

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Physics

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CBSE Gujarat Board Haryana Board

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Class 10 Class 12

Two cities are 150 km apart. electric power is sent from one city to another city through copper wires. The fall of potential per km is 8 V and the average resistance per km is 8 V and the average resistance per km is 0.5 space straight capital omega. The power loss in the wire is,

  • 19.2 W

  • 19.2 kW

  • 19.2 J

  • 12.2 kW


B.

19.2 kW

Potential difference (drop) between two cities = 150 x 8 = 1200 V

Average resistance of total wire = 0.5 x 150 = 75 space straight capital omega
Power loss, P = straight V squared over straight R equals fraction numerator 1200 space x space 1200 over denominator 75 end fraction equals 19200 space W 
                  = 19.2 kW

Potential difference (drop) between two cities = 150 x 8 = 1200 V

Average resistance of total wire = 0.5 x 150 = 75 space straight capital omega
Power loss, P = straight V squared over straight R equals fraction numerator 1200 space x space 1200 over denominator 75 end fraction equals 19200 space W 
                  = 19.2 kW

742 Views

Is work a scalar or a vector quantity?

Work is dot product of two vectors. i.e. F with rightwards arrow on top times S with rightwards arrow on top.

And dot product is a scalar quantity. Therefore, work is a scalar quantity. 
1450 Views

Define watt.

Power is said to be one watt if one joule of work is done in one second. 
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Define the unit joule.

Work done is said to be one joule if one newton of  force displaces the body through a distance of one meter in the direction of applied  force .
799 Views

What is watt?

SI unit of power is Watt. 
773 Views

What are different units of energy?

The different units of energy are :

(i) Joule            
(ii) Erg
(iii) eV            
(iv) KWh
(v) Calorie.

804 Views