500 cm³ of water at 100°C is added to another 500 cm³ of water at a temperature of 30°C. Assuming no heat is lost to the surrounding, what is the final temperature of the mixture when thermal equilibrium is achieved?

Electromagnetic induction. a coil of wire contains n turns and has an electrical resistance r. the radius of each turn is a. initially, inside the coil there exists a uniform magnetic field of magnitude b0 parallel to the axis of the coil. the magnetic field is then reduced slowly. the current induced in the coil is i. how long does it take for the magnitude of the uniform field to drop to zero?