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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

Water falls from a height of 60 m at the rate of 15 kg /s to operate a turbine. The losses due to frictional 

  • 8.1 kW

  • 10.2 kW

  • 12.3 kW

  • 7.0 kW


A.

8.1 kW

Power generated by the turbine is,

Pgenerated = Pinput  x 90/100


equals Mgh over straight t space straight x 90 over 100
Putting space the space given space values
straight M over straight t space straight x space 15 space kg divided by straight s comma space straight g space equals space 10 space straight m divided by straight s squared space comma space straight h space equals 60 space straight m
straight P subscript generated space end subscript space space equals space left parenthesis 15 space straight x space 10 space straight x 60 right parenthesis space straight x 90 over 100
space equals space 8.1 space kW

Power generated by the turbine is,

Pgenerated = Pinput  x 90/100


equals Mgh over straight t space straight x 90 over 100
Putting space the space given space values
straight M over straight t space straight x space 15 space kg divided by straight s comma space straight g space equals space 10 space straight m divided by straight s squared space comma space straight h space equals 60 space straight m
straight P subscript generated space end subscript space space equals space left parenthesis 15 space straight x space 10 space straight x 60 right parenthesis space straight x 90 over 100
space equals space 8.1 space kW

1571 Views

Define watt.

Power is said to be one watt if one joule of work is done in one second. 
860 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

What are different units of energy?

The different units of energy are :

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

804 Views

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