A solid brass ball of mass 1.39 kg and density 8,470 kg/m3 hangs at rest from the end of a string. The tension in the string is measured and recorded. The ball is then lowered by the string into a container of oil so that it is completely submerged in the oil. The new value of the string tension is then found to be 12.3 N. What is the density of the oil?
Answer: 830 kg/m3
