¿Cuál es la masa de un objeto cuya masa es de 400 J y energía cinética de 107J?

What happens when a rubber rod is rubbed with a piece of fur?

Arigid tank is divided into two equal parts by a partition. one part of the tank contains 3 kg of compressed liquid water at 400 kpa and 60°c while the other part is evacuated. the partition is now removed, and the water expands to fill the entire tank. determine the entropy change of water during this process, if the final pressure in the tank is 40 kpa. use steam tables.

Could we see a galaxy that is 20 billion light-years away?