Answer to Question #146314 in Physics for Chan

Question

A piece of irregular shape gold ring is of unknown mass. In the absence of weighing scale, and the only available to you is a graduated cylinder and water. If the gold ring is immersed to the graduated cylinder with water, the volume of water increases to 4.0 cubic centimeter, what is the mass of the gold ring?

Answer 1

By definition, the dencity of gold is:

$$\rho = \dfrac{m}{V}$$

We know that $V = 4cm^3$ and $\rho = 19.32\space g/cm^3$ (if we assume that the ring is made of pure gold). Then expressing the mass $m$, obtain:

$$m = \rho V = 19.32\cdot 4 = 77.28g$$

Answer. 77.28 g.