Is it possible to have a net torque when all of the forces sum to zero? explain.

The consumption of fossil fuels could be

A175 g lump of molten lead at its melting point (327 c) is placed into 55.0 g of water at 20.0 c. the specific heat of lead is 130.j/kg c and the hf of lead is 20,400 j/kg. when the lead and the water have reached equilibrium, what is the temperature of the mixture?

What is relative velocity? in which condition is relative velocity known by adding the velocity of the first body and that of the second body