Name
Date
Per
CASTLE Unit 4 - Activity 1
How do differences in
pressure affect the flow
of a fluid?
Set Up
A two liter soda bottle is filled with
water. There are three holes at different
heights on the bottle. Open all three
three holes at the same time.
Observation(s):
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 =
Observe the flow rate from each hole.
F
). How do the
A
pressures at the positions of the holes compare. Explain.
€
6.
What appears to be the relationship between the pressure at the hole and
the flow rate from the hole?
©Modeling Workshop Project 2010, STL Group RPR, DJR
1
C4 ACT 1 v1.2
A two liter soda bottle is filled with
water. There are two holes of
different diamters at the same height
on the bottle. Open both holes at the
same time
7.
How do the sizes of the holes compare?
8.
How do the speeds of the water coming from the holes compare?
9.
Compare the flow rates from the holes.
10.
How do the pressures at the positions of the holes compare?
Explain.
11.
What is the effect of changing hole size on flow rate when the
pressure is constant?
12.
Draw an analogy between this situation and an electric circuit.
Observe the flow rate from each
hole.
©Modeling Workshop Project 2010, STL Group RPR, DJR
2
C4 ACT 1 v1.2
Prediction(s)
Observation(s)
How do differences in
pressure affect the flow
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 2010, STL Group RPR, DJR
3
C4 ACT 1 v1.2
Prediction(s)
Observation(s)
How do differences in
pressure affect the flow
of a fluid?
1. How does the pressure of the water, relative to the
holes, compare for each bottle.
2. How do the sizes of the holes compare?
3. What happened when the hose was “unkinked.”
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?”
4. Why does the water in each bottle behave as you
observed?
©Modeling Workshop Project 2010, STL Group RPR, DJR
4
C4 ACT 1 v1.2
Prediction(s)
Observation(s)
How do differences in
pressure affect the flow
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 2010, STL Group RPR, DJR
5
C4 ACT 1 v1.2
Prediction(s)
Observation(s)
How do differences in
pressure affect the flow
of a fluid?
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 2010, STL Group RPR, DJR
6
C4 ACT 1 v1.2
Prediction(s)
Observation(s)
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
3-liter bottle
filled higher
than 1-liter
bottle
A 3-liter bottle is connected to a one-liter bottle
by a clamped tube.
Observations
Water level
remains the
same
Water flows
from 3-liter
to 1-liter
bottle
1-liter bottle
filled higher
than 3-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
©Modeling Workshop Project 2010, STL Group RPR, DJR
7
C4 ACT 1 v1.2