Question

An object has a mass of 20 kg and a volume of 5 mL. What is the object's density?

the answer is 4 kg/cm 3. but how do I get to this conclusion?

Answer 1

Think of a cube that is 1 cm by 1 cm by 1 cm. The volume of this cube is 1*1*1 = 1 cubic cm = cm^3. This is equivalent to 1 mL by definition

So the object's volume of 5 mL is the same as 5 cm^3.

To get the density of an object, we divide the mass over volume

density = (mass)/(volume)

density = (20 kg)/(5 mL)

density = (20 kg)/(5 cm^3)

density = (20/5) (kg/cm^3)

density = 4 kg/cm^3

The density is 4 kilograms per cubic centimeter. In other words, each cubic centimeter of volume has about 4 kilograms of material.