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Physics

Nine Standard >> Power

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Power and the relationship between work and power

The rate of work done with respect to time is called power. That is the work done in unit time is power. So the power of a machine will be just by the work done in unit time.

The rate of doing work with respect to time is called power.

    Power=\(\frac{Work}{Time}\)
  or Work=Power \(\times\) time

Unit of Power:

In the CGS system, the unit is erg/s
In the SI system, the unit is J/s= watt

1 watt=1 J/s
         =\(10^{7}\) erg/s

The power of a machine is 500 watt means that the machine can perform 500 J of work in a 1s.
The power of a machine is 1 kW means that the machine can perform 1000 J of work in a 1s.

Gravitational unit of work:

In the CGS system, the unit is g.cm/s
In the SI system, the unit is kg.m/s

Relation between g.cm/s and erg/s is  
        1g.cm/s=980 erg/s

Relation between g.cm/s and erg/s is 
        1kg.m/s=9.8 J/s

Work in not related to time but power is related to time. Work done in unit time is power.
 

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