Why is it difficult to move heavy furniture?

Heavy furniture exerts a high pressure – force per unit area – downwards. If both the contact surfaces of the furniture and the surface of the floor are very rough, the surfaces adhere to each other. To move the furniture we have to overcome this force known as static friction. It is smaller if the surfaces are smoother. 

During movement, it gets converted into dynamic friction. It is easier to transport heavy objects on wheels. Forces of friction always produce heat. In the Stone Age, human beings used this heat to make fire.