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

weight of the box is given as

here this is placed on the inclined of angle 42 degree

now this weight will have two components one is along the incline other is perpendicular to it

so here we need to apply a force parallel to incline opposite to its component of weight

so here the component of weight is given as

here we have

so it requires 75 n force to move it upwards