Why is water needed to determine specific heat of a metal object?

Because it is easier to calculate an item in its solid form then in its liquid state. If you burn a metal on a burner, eventually it will melt making it harder to measure.This previous answer is not much help to you & I will give you another answer. The definition of Specific Heat is :- the number of Calories of heat energy required to raise the temperature of 1 gram of any substance , by an amount of 1Centigrade Degree. A century or more, ago, it was decided by scientists that they would use pure water as a control standard for Specific Heat . To raise the temp of 1gram of pure water 1centigrade degree, the amount of heat required was given the name Calorie. So, the S.H. Of Water is 1 Cal/ gram/ degree C. When we say that the S.H. of pure Copper is 8.93 Cal/gram/degreeC , this indicates to us that Copper needs heaps more heat energy to achieve what we achieve with Water. Substances with a large S.H. 'soak up' heat to a greater degree than water. Water was chosen as a standard substance with which we compare other less common substances. For the same reason as we chose water to graduate thermometers, with zero as freezing temperature and 100 as boiling temperature . Water is the most common substance used by people and is the same all over the entire world. Now, to answer your real question. Water is not needed to determine Specific Heat (S.H.) Water is used as the basis upon which S.H.of all other substances are compared Some values of S.H. for other substances. Iron 7.8 Glass 2.7 Alumimium 2.7 Wood 0.7 And in all these examples the 'unit' of S.H. Is always, Calorie per gram per degree Centigrade