Exploring Density -- Why Don't Ships Sink in the Red Sea?

 Exploring Density
Why Don't Ships Sink in Red Sea?

The City School arranged a science fair. Children from the entire region enthusiastically participated in this project. 

The main goal of this activity was to develop students' scientific knowledge and skills so they could apply them to problems in real life.

Discovering Density was the subject chosen by my students from Class 5C.

Why don't ships sink in the Red Sea, I heard them ask.

The investigation's main issue was resolved, and we got to work solving it together.

We eventually agreed that the Red Sea is the saltiest sea in the world and that salt water has a higher density than freshwater, which keeps ships from sinking and allows them to float.

After developing the hypothesis, we intended to execute the test to validate and assess it.

Some examples of density for different fluids and materials was collected by researching on internet which are:

• - Fresh water: 1,000 kg/m3

• - Salt water: around 1,025 kg/m3

• - Certain oils: around 850 kg/m3 

• - Steel: 8,000 kg/m3

• - Wood: around 700 kg/m3

To test whether chicken eggs float or sink in saline water, we chose to utilise them for this purpose. Because it was affordable and reasonable to carry out in a classroom, this was the most practical way to test our theory.

Items from Class 5C students were brought in to the Science Lab for the fair test.

Items Required

the required items were;

• three chicken eggs

• warm water

• salt

• 3 beakers

• electronic weight machine

• calculator

Experimental Setup

Luke warm water in three glasses was taken. 

In the first glass the water was fresh and plain without salt.

The egg sank down. 

when the density of egg was calculated using formula of density 

density = mass / volume

The mass of the chicken egg was 58g and the volume of the egg was 50cm3

Using the formula the density of chicken egg was calculated to be 58/50 = 1.16g/cm3

then the density of fresh water was calculated. 

the density of 250 ml of fresh water was 1.02 g/cm3

When the densities of chicken egg and fresh water was compared, the density of chicken egg was more than that of fresh water i.e.

density of water < density of chicken egg.

1.02 < 1.16

Therefore the egg sank in the water.

Now, to increase the density of water 30 g of salt was added in the second jar which had 250 ml of Luke warm water. A saturated homogeneous solution was formed by vigorously mixing the salt in water. Now the water was salty. 

The density of the salty water was 1.20g/cm3

the density of chicken egg was 1.16g/cm3

When the egg of 1.16g/cm3 was left in the beaker of salty water of density 1.20g/cm3 the egg started floating on the surface of the water.

i,e. the density of salt water  >  density of chicken egg

1.20 > 1.16

This was so fun for kids to observe that actually when the density of egg was less than that of the water, the egg began to float on the surface of the water.

We then tested a broken egg as well.

The broken egg had the path for air to go and it stayed in the middle of the water and was continuously moving in circular direction.

Conclusion

Students came to the conclusion that because the Red Sea is the world's saltiest sea (41 parts of salt per 1000 parts of water) and the world's warmest sea (temperatures ranging from 68 degrees to 87.8 degrees F), ships never sank in the sea's salinity.

Fun Fact

Students also tried out a fun fact. After placing the egg inside the beaker, they divided it in half, adding salty water to one half and fresh water to the other. In the centre of the beaker, the egg floats.

 

Therefore, it was also noticed that fresh water was sinking to the bottom because its density was lower than that of an egg while salty water was pushing the egg upwards since its density was more than that of an egg. As a result, the egg floated in the middle of the beaker.

Then we started working on our presentation