A mass of 15 kg of air in a piston-cylinder device is heated from 25 o C to 77 o C by passing current through a resistance heater inside the cylinder. The pressure inside the cylinder is help constant at 300 kPa during this process and a heat loss of 60 kJ occurs. Calculate the electric energy supplied in kWh.

The electrical energy supplied is 0.233 kWh

Explanation:

Given :

Mass of air kg

Initial temperature 298 K

Final temperature 350 K

Heat loss kJ

From the first law of thermodynamics,

We know that internal energy is proportional to difference of temperature,

Now we need answer into kWh so ( 1 kWh = 3600 kJ ).

So we need to multiply ( )

      kWh

      kWh

Therefore, the electrical energy supplied 0.233 kWh

they start with the same

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