Transcript Flotation - Vicphysics

Flotation
Liam King, Arthur Kyriakopoulos, Vincent Lu (MSC)
Flotation
• A piece of a flattened raisin, which is dropped
into a glass of soda water, periodically sinks
and goes back to the surface. Investigate the
dependence of the period of these oscillations
on various parameters. (Note: a combination
of vinegar and bicarb of soda in water also
works quite well).
Aim
• The aim of this experiment was to
understand why raisins oscillated in
soda water.
• And if so, what the correlation between
the period of oscillation and mass of the
raisin is.
Hypothesis
• The more mass a raisin has, the less it will
oscillate in the water.
What is actually happening?
•
•
•
•
Bubbles are produced and this causes the raisin to
oscillate.
When the raisins are put in the water and vinegar they
sink.
The bubbles cause the raisins to rise.
This means that the density of the sultanas change as
they are made less dense by external gas bubbles.
Variables
●
●
●
●
●
●
●
●
●
●
Period of oscillation (Dependent)
Mass of raisin (independent)
Surface area of raisin (control)
Temperature of room (control)
How the raisin was dried and treated (control)
Fizziness of soda water (control)
Width of beaker (control)
Volume of liquid (control)
Temperature of water (control)
Oscillation height (5cm) (control)
Theory
• A raisin will oscillate due to carbon dioxide
bubbles getting caught in the ridges in the
raisins.
• Once the bubbles pop (being exposed to
air), the raisins will return to the bottom of
the beaker.
Materials
•
•
•
•
•
•
•
•
Water
Vinegar
Bicarb soda
Raisins
Scale
Spoon
Beaker
Stopwatch
Method
•
•
•
•
Mix water (100ml) and vinegar (150ml) in a beaker.
Add bicarb soda (5g) to the beaker.
Add one raisin.
Use a stopwatch to measure the length of time
between each oscillation of the raisin (how long it takes
to get to the top and how long it takes to get to the
bottom of the beaker).
Results
Raisin 1,3,4,9
Surface area (mm)
5*5*5
Volume of raisin (mL^3)
0.2
Results
Raisin 1
Mass (212 grams)
Period of movement
Time (seconds)
1
6.14
2
5.28
3
2.56
4
1.35
5
10.28
6
8.1
7
35.43
8
3.41
9
8.35
10
0.89
Odd number
indicates a
movement up
and even
numbers
indicate a
movement
down from the
raisin.
Results
Raisin 3
Mass (205 grams)
Period of movement
Time (seconds)
1
4.08
2
2.93
3
3.59
4
1.96
5
3.48
6
8.41
7
4.91
8
9.2
9
4.73
10
3.61
Odd number
indicates a
movement up
and even
numbers
indicate a
movement
down from the
raisin.
Results
Raisin 4
Mass (242 grams)
Period of movement
Time (seconds)
1
6.42
2
1.22
3
2.99
4
7.06
5
26
6
3.85
7
8
9
10
Odd number
indicates a
movement up
and even
numbers
indicate a
movement
down from the
raisin.
Results
Raisin 9
Mass (250 grams)
Period of movement
Time (seconds)
1
2.58
2
2.51
3
3.59
4
0.94
5
1.9
6
1.43
7
8
9
10
Odd number
indicates a
movement up
and even
numbers
indicate a
movement
down from the
raisin.
Results
Conclusion
• The hypothesis was supported that raisins
with a greater mass will oscillate less. This
is shown from our results as raisin 3 with
the smallest mass oscillated the most and
raisin 9 with the greatest mass oscillated
the least.