CASTLE Unit 4 - Activity 1
Pressure in Fluids
Part 1
Setup
Date ______________________
Period _________
Observations
How do differences in
pressure affect the flow
of a fluid?
1.
Describe the flow rate from each hole.
2.
How do the sizes of the holes compare?
3.
Consider the weight of the water above each hole. How do these amounts
compare? Explain.
4.
How do the cross-sectional areas of the bottle at the positions of the holes
compare?
5.
Pressure is defined as the force per unit area. ( P =
6.
What appears to be the relationship between the pressure at the hole and
the flow rate from the hole?
A two liter soda bottle is filled with
water. There are three identical holes at
different heights on the bottle. All
three holes will be opened at the same
time.
Predict how the flow rates from each
hole will compare.
Name________________________________________
F
). How do the
A
pressures at the positions of the holes compare. Explain.
©Modeling Workshop Project 2013, STL Group RPR, DJR
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C4 ACT 1 v1.13
©Modeling Workshop Project 2013, STL Group RPR, DJR
2
C4 ACT 1 v1.13
Part 2
How do differences in
resistance affect the flow
rate of a fluid?
Setup
A two liter soda bottle is filled with
water. There are two holes of different
diameters at the same height on the
bottle. Both holes will be opened at the
same time.
Observations
1.
How do the sizes of the holes compare?
2.
How do the speeds of the water coming from the holes compare?
3.
Compare the flow rates from the holes.
4.
How do the pressures at the positions of the holes compare?
Explain.
5.
What is the effect of changing hole size on flow rate when the
pressure is constant?
6.
Develop an analogy between this situation and an electric circuit.
Predict how you think the flow rates will
compare from the two holes.
©Modeling Workshop Project 2013, STL Group RPR, DJR
3
C4 ACT 1 v1.13
Part 3
Setup
Observations
How do differences in
pressure affect the flow
rate of a fluid?
1. Describe the flow rate from each hole.
2. How does the size of each hole compare to the other holes?
3. How does the pressure of the water with respect to the hole
compare for the two bottles.
A single 2-liter soda bottle and a
double (end to end) 2-liter soda bottle
are filled with water. This simulates a
one-cell battery and a battery of two
cells in series.
Allow water to drain from each bottle
from the holes that are at the same
level in each battery.
4. Describe the relationship between the pressure of the water and
the flow rate when the size of the hole is held constant?
How will the flow rates from the two
bottles compare?
©Modeling Workshop Project 2013, STL Group RPR, DJR
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C4 ACT 1 v1.13
Part 4
Setup
How do differences in
pressure affect the flow
rate of a fluid?
Observations
1. How does the pressure of the water, at the positions
of the holes, compare for each bottle.
Part 5
There are three 2-liter soda bottles. Two green bottles
are connected together side by side (in parallel) and
were then connected to a single clear bottle. All three are
filled to the same level with the hose between the single
and double bottles kinked. What do you think will
happen to the water level in the three bottles when the
hose is “unkinked?”
2. How do the sizes of the holes compare?
3. What happened when the hose was “unkinked.”
4. Why does the water in each bottle behave as you
observed?
©Modeling Workshop Project 2013, STL Group RPR, DJR
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C4 ACT 1 v1.13
Part 5
Setup
Observations
How do differences in
pressure affect the flow
rate of a fluid?
1. How does the water flow rate for each individual
bucket compare to the flow rate when the valves for
both buckets were open?
There are two 5-gallon buckets connected together
with a pipe that also has two valves and a drain
spout between the buckets. This simulates batteries
connected in parallel. The buckets are filled to the
same level.
How will the flow rate compare when the valve
from only one bucket is open to when the valves
from both buckets are open?
2. What factors affected the flow rates you observed?
©Modeling Workshop Project 2013, STL Group RPR, DJR
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C4 ACT 1 v1.13
Part 6
Setup
How do differences in
pressure affect the flow
rate of a fluid?
Observations
1. How does the water flow rate for each individual container
compare to the flow rate of the others?
There are 4 different diameter bottles to simulate
the difference between AAA, AA, C and D cells.
Each bottle has an identical size hole at the same
level near the bottom of the bottle. Each bottle is
filled to the same level. All bottles are allowed to
drain simultaneously into the sink.
How will the flow rates compare?
2. What factors affected the flow rates you observed?
©Modeling Workshop Project 2013, STL Group RPR, DJR
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C4 ACT 1 v1.13
Part 7
Setup
Observations
How do differences in
pressure affect the flow
of a fluid?
Observations
Water level
remains the
same
Water flows
from 3-liter to
1-liter bottle
Water flows
from1-liter to
3-liter bottle
Both bottles filled
to the same level
A 3-liter bottle is connected to a one-liter bottle
by a clamped tube.
Predictions
Water level
remains the
same
Water flows
from 3-liter
to 1-liter
bottle
3-liter bottle filled
higher than 1-liter
bottle
Water flows
from1-liter to
3-liter bottle
Both bottles
filled to the
same level
3-liter bottle
filled higher
than 1-liter
bottle
1-liter bottle filled
higher than 3-liter
bottle
1-liter bottle
filled higher
than 3-liter
bottle
©Modeling Workshop Project 2013, STL Group RPR, DJR
8
C4 ACT 1 v1.13