A block of aluminum at 204°C is put into 1.00 kg of water at
24.0°C. They come to equilibrium
at 28.5°C. What was the mass of
the aluminum block?
(Unit=kg)

Students in an introductory physics lab are performing an experiment with a parallel-plate capacitor made of two circular aluminum plates, each 11 cm in diameter, separated by 1.0 cm. how much charge can be added to each of the plates before a spark jumps between the two plates? for such flat electrodes, assume that value of 3×106n/c of the field causes a spark.