# Friction and energy

I think I have a bit of a misunderstanding that I can't resolve... Let's say I exert a force on a block of wood that rests on a table with friction. The force I'm exerting has the same magnitude as the friction(but in opposite direction) so that the net force is zero, and the block of wood moves with constant velocity.

My question here is; the work done by the force I exert would be the same as the work done by friction(but one will be plus and the other will be minus) therefore work done by the force I exert and the work done by friction would cancel, resulting in the net work being zero.

But the thing is; by friction, the block of wood gets heat.

Then does this mean that even though the net work is zero, thermal energy is produced?? What am I not thinking correctly here?? Can anyone please help?

• Work has no associated direction. For example, if I rub my hand in a circle across the wood, the work done is the friction force times the circumference of the circle. By you reasoning, work would be zero. – James Sep 22 '16 at 17:51