1. Group 5: Beatrice, May, Pena, Phuntsok.
Group 4 Project
Group 5: Beatrice, May, Pena, Phuntsok.

2. Buoyancy in sea and lake water and the factors affecting it.
We decided to investigate on the different buoyancy in Devon’s sea and Ley.
Our hypothesis: Buoyancy in sea water is greater than that of the Ley’s water as salty water is more dense than fresh water.
Aim: Prove that our hypothesis is right and explain.

3. Equipment used 1 cylinder (500ml) 1 magnifying glass 1 tray
1 kick sampling net
1 microscope
1 mass
1 crucible
4 vials
1 microwave
Weighing scale
2 petridishes

4. First Steps This morning we went over the final plans of the day.
When we went to get our equipment we faced our first problem: the center didn’t have a Newton meter, an essential equipment to measure Buoyancy.
Solution: with the help of Dr Adedapo and Mr Beardsell we found an alternative that consisted of using a mass(vial with stones in) and taking note of how deep it sunk into the water (contained in a 500ml cylinder).

5. Explaining our hypothesis: Chemistry experiment
Why is salty water denser that fresh water?
Method:
-Take 2 crucibles and measure their weight without anything in them.
-Weight of the bowls with 5 ml ³ of each type of water.
-Put the bowls and heat in a microwave until all the water evaporates.
-Measure the weight of the bowls.

6. Chemistry Results Conclusion:
Variable
Weight in fresh water
Weight in sea water
Weight of crucibles without water
19 g
Weight crucibles with 5 ml³
24 g
23 g
Weight of crucibles
19.6 g
Conclusion:
We can conclude that there is more salt in sea water then in the Ley’s water, therefore, there is more buoyancy in sea water.

7. Buoyancy experiment : Physics
Method: We went to the Ley and Sea and sample 1L of water in separate bottles and brought them back to the lab. Variables: Dependent – Ley and Sea water Independent – Buoyancy Controlled – 500 ml cylinder, mass

8. Diagram: Physics Experiment
440ml
440ml
cylinder
340ml
330ml
mass
320 ml
310ml
Sample of Ley water in a cylinder with a mass that floats at 320 ml
Sample of sea water in a cylinder with a mass that floats at 310 ml

9. Results of physics experiment and conclusion
Our hypothesis is not correct as a matter of fact the experiment proves that a mass floats higher in sea water than that of the Ley’s water. As we were proven wrong, we came to ask ourselves: Is the Ley’s water pure fresh water? This led to another series of experiments.

10. EVS Experiment: Organisms in different water environment
We used the method of kick sampling to discover the organisms living in the two different water bodies. To indentify the organisms we used a Key provided by the centre. In each case the same amount of water ( 1L) was sampled. The density of organisms found determine the amount of pollution contained in the water. Pollution is more particles, and would make the mass float more.
Sample of fresh water in a tray
Sample of sea water in a tray

11. EVS Experiment results
Ley:
Sea:
1 sea water shrimp carrying a baby
2 Biting midge Larva
Over 15 non biting midge larva
8 fresh water shrimp
1 swimming Mayfly Nymph
1 Demoiselle Damselfly
We can see that the Ley is much more rich in organisms. It presents a varied amount of species of invertebrates. But on the other side the sea has a fertile environment (as we identified a baby shrimp).

12. Biology Experiment
See Poster

13. Proof
To prove that all of the organisms in the Ley’s water were the ones impacting the density of the water and therefore the Buoyancy we redid the first Physics experiment with fresh tap water.
440ml
320 ml
300 ml
Sample of fresh tap water in a cylinder with a mass that floats at 300 ml

14. Conclusion and Evaluation
Ley’s water buoyancy is in fact greater than salt water due to the higher density of living microscopic organisms that we identified in our samples.
Because we were wrong with our first hypothesis, which we thought would lead to the greater buoyancy in salt water, we changed our scope to the factors that were causing the greater buoyancy in Ley’s lake water.