Question

The air in a room has a mass of 50kg and a specific heat of 1,000 J/(kg.C). What is the change in the thermal energy of the air when it warms from 20 degrees C to 30 degrees C?

Answer 1

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)