## 6 Common Problems of Material Density

- Category: Junior High
- Written by fisikastudycenter

physics.fisikastudycenter.com - Learning 5 Common problems of material density, grade 7 of yunior high school physics.

**Density**

The density of a material is equal to its mass divided by its volume:

where:

ρ = density in kg/m^{3}

m = mass in kg

V = volume in m^{3}

**Problem 1**

A body of 300 g with a volume of 400 cm^{3}. Find the density of the body show your answer in kg/m^{3}!

**Answer**

The data:

m = 300 g

V = 400 cm^{3}

So then :

ρ = m/V = 300 / 400 = 0.75 g/cm^{3}

ρ = 0.75 x 1000 = 750 kg/m^{3}

**Problem 2**

A block of a density of 700 kg/m^{3} has 2 kg of mass. Find the the volume of the block show in cm^{3} and liter!

**Answer**

The data:

m = 2 kg

ρ = 700 kg/m^{3}

So then:

V = m / ρ

V = 2 / 2000 m^{3}

V = (2/2000) x 1000000 cm^{3} = 1000 cm^{3}

in liter

V = 1000 cm^{3} = 1dm^{3} = 1 liter

**Problem 3**

A block with its lenght, widht and height are 20 cm, 5 cm and 6 cm respectively. Find mass of the block when its density is 0.8 g/cm^{3}!

**Answer**

First find the volume:

V = p x l x t = 20 cm x 5 cm x 6 cm = 600 cm^{3}

So then the mass of the block m = ρ x V = 0,8 x 600 = 480 gram

**Problem 4**

An experiment to measure the densty of a body using below equipment.

From the data you get, find the density of the body note that the mass of the body is 300 gram!

**Answer**

Data:

Volume V = 300 ml = 300 cm ^{3} (terlihat dari gelas ukur)

Mass m = 300 gram

So then:

ρ = m/V = 300 / 300 = 1 g/cm^{3}

Note:

1 ml = 1 cc = 1 cm^{3}

**Problem 5**

A student does an experiment to measure the density of a rock using below equipment. What is the density of the rock show in g/cm^{3}!

**Answer**

m = 300 gram

V = 500 − 300 = 200 ml = 200 cm^{3}

ρ = m/V

ρ = 300 / 200 = 1,5 g/cm^{3}

**Problem 6**

An experiment below is to measure the density of a material. What is the density of the material?

**Answer**

Mass measurement shows the mass of the material m = 250 gram

Volume measurement shows the volume of the material V = 500 − 300 = 200 ml = 200 cm^{3}

The density of a material is equal to its mass divided by its volume.

So then:

ρ = m / V

ρ = 250 / 200 = 1,25 g/cm^{3}