We know the change of thermal energy is proportional to the specific heat of the matter, its mass and the change of temperatures, according the following formula:
Q = C*m*(Tf-Ti)
where:
Q is the heat added or removed (in joules, J)
C is the specific heat of the matter, in our case air 1,000 J/(Kg*C)
m is the mass, in our case 50 kg of air
Tf is final temperature
Ti is initial temperature
then:
Q = 1000 * 50 * (30-20) = 500,000 Joules
That means that 500,000 joules need to be added to increase temperature of the room 10 ÂşC (from 20 to 30 ÂşC)
