Answer to Question #152210 in Physics for Isaac Camilleri

Question

John needs to find the mass of a larger steel bolt but does not have access to a balance. He knows that the density of steel is 8050kg/m^3.
Describe how can he accurately find the mass of the bolt using density.

Answer 1

He can use the relation between the mass and the volume of a body:

$$m = \rho V$$

where $\rho = 8050kg/m^3$ is the density of the steel, and $V$ is the volume of the bolt. Thus, if he find the volume of the bolt, he will calculate its mass. One of the simplest way to find a volume is to take a measuring cup with some definded water level (say, $300cm^3$ ) and put the bolt into this cup. The difference between the initial and final water levels will be exactly equal to the volume of the bolt.