Heat can also be produced by the impact of imperfectly elastic bodies as well as by friction. This is the case, for instance, when we produce fire by striking flint against steel, or when an iron bar is worked for some time by powerful blows of the hammer.
Hermann von HelmholtzRelated topics
case elastic fire hammer heat instance iron produce steel wellRelated quotes
We need to live life not only for ourselves. Pray quietly for everyone. Do not reject or humiliate anyone. Our thoughts and words have a powerful impact on the world around us. Pray with tears for everyone - for the sick, the weak, for the sinners. Pray for those who have no one to pray for them.
Nikolay Guryanov