A student carries out an experiment to determine the density of the material from which two identical solid objects are made. She uses a balance and a measuring cylinder containing a fixed volume of liquid. The diagrams show different stages of her experiment, with some of the readings on the balance and some on the measuring cylinder. Which calculation should be used to determine the density of the material from which the objects are made?

Answer:

3) D

Mass of cylinder with 250cm³ = 170g
Then, the mass is increased to 470g when the object is submerged.
Mass of object = 470-170 = 300g.

When two objects are placed in the measuring cylinder, volume increases from 250 to 350.
Volume of two objects = 350-250 = 100cm³
Volume of 1 object = 100/2 = 50cm³
Density = Mass/Volume = (300/50) g/cm³