Fluids mechanic lab#1 done
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Transcript of Fluids mechanic lab#1 done
Name: Manzi Roger Dusab. Id: 460234 Lab Partners: Evans Steven
Instructor’s name: Dr. Jung
EGR 342 Fluids Mechanics
Section C
Lab# 1
Abstract
Always wondered what the atmospheric pressure really is capable of. In this lab, all experiments
that were performed discussed and helped explain different effect of pressure. Magdeburg plates
were used to describe these different properties of pressure. This report describes the lab
procedures and setups for each of the six experiments performed in this lab. It also contains all
observations and results from the lab.
I. Introduction
In this two hours experiment, Magdeburg plates were used to demonstrate the concept of
atmospheric pressure. Using those plates and other equipment, various experiments were run. A
test to determine the total force on the plates which is equal to the atmospheric pressure on the
plates; experimentally determining the force holding the plates together; measuring the force
required to break the plates apart; determining the effect of air pressure on the boiling
temperature of water, investigating the effect of air pressure on the size of a balloon, and
examining the effect of air pressure on suction cup.
II. Experimental Setup
The equipment used in this lab includes:
The instruments are labeled below:
The instructions on how to assemble those instruments are given before each experiment.
Note: Besides the above listed equipment, we also used a computer equipped with Data studio
software, and a pressure sensor.
III. Results
1. Activity 1: Determining the total force on the plates: equal to the force of atmospheric
pressure on the plates
1. The diameter of the surface enclosed by the O-ring was determined by measuring
the outer and inner diameters(D2, and D1) of the O-ring. The two diameters were
then averaged.
2. The Magdeburg plates were assembled as described above, and then connected to
the computer with the Science Work software.
3. A vacuum was then pulled in the interior chamber with the vacuum pump.
4. Using Data studio software and the pressure sensor, the pressure inside the
chamber was measured and recorded.
5. The atmospheric pressure was also measured and recorded.
6. This experiment was run twice. First using the bigger O-ring, and second using
the small O-ring
Used formula:
Fn = (Pap − Pr ) ∗ 𝜋𝑟2 Bigger O-ring
D1 D2 Pap Pr r Fn
0.083 0.089 99700 24600 o.o43 436.02
m m N/m2 N/m2 m N
Smaller O-ring
D1 D2 Pap Pr r Fn
0.056 0.064 99800 24700 0.03 212.23
m m N/m2 N/m2 m N
2. Activity 2: Experimentally determining the force holding the plates together. ( small
ring)
1. The plates were assembled using the small O-ring and the Vacuum was pulled in the
inter-plate space.
2. Having a light, strong student stand on a bathroom scare holding one handle of the
Magdeburg plates, a stronger person knelt down in front and pulled on the second
handle.
3. Another team member was monitoring the red-outs on the scale a recorded the lowest
and the highest value on the scale.
4. The two plates were pulled apart with a slow but steadily increasing force while the
other team member carefully observe how the reading on the scale changes.
The Equipment assembly looked like:
Initial Scale read-Out Final Scale read-Out Force to break the plates
apart
155 190 35 155.75
lbs lbs lbs N
The Force required to break the two plates apart is exactly the same force holding them
together. Fa= 155.75 N
3. Activity 3: Measuring the vacuum pulled and observe the rate of decay using sience
workshop.
In this experiment we use Data studio, a computer and a pressure sensor to monitor the pressure
in the chamber between the plates.
1. The Magdeburg plates were assembled as shown below, so that the chamber pressure can be
monitored with a pressure sensor and a data studio equipped computer
2. The sampling rate on the pressure sensor was sat to 1 sample/s; and data collection started
right away.
3. A vacuum was pulled in the chamber with the syringe and the plates were allowed to sit
undisturbed for a few minutes. Every time or so, one of the team members was supposed to try to
break the plates apart.
4. The pressure at which the team member was able to successfully break apart the plates was
recorded, and then proceeded with calculations to compute for the force needed to break these
two apart
Pressure Area Force
93 “ac” : are of the inner chamber 93.ac
KPa m2 KN
0
20
40
60
80
100
120
0 20 40 60 80 100 120
Ab
s. P
ress
ure
( k
Pa)
Time (s)
Absolute pressure vs. Time
4. Activity 4: Determining the effect of air pressure on the boiling temperature of
water
In this part, water was boiled by adjusting the air pressure rather than the temperature of
the liquid.
1. The Magdeburg plates were assembled with an extra cylinder, plate and two O-rings
from the accessories kit. The picture of the setup is shown below.
2. The given plastic cup was filled with hot coffee/ in this case very hot tap water can be
used.
3. The temperature of the liquid was measured and recorded.
4. Data recording was started as the pressure was being monitored. A vacuum was pulled
in the cylinder using a syringe, and the liquid was observed carefully and had to
observations noted down.
5. Afterwards, the connection was loosened slowly to release the vacuum, and then had
the temperature of the liquid measured.
Temperatures: T1 = 59 oC
T2 = 86 oC
Observation for #4.
The water started boiling, and the cylindrical container seemed
very bubbly as we approached 40 KPa, but the boiling was not
intense as it was seen from the next-table group.
5. Activity 5: Investigating the effect of Pressure on the size of a ballon
1. The Magdeburg apparatus is assembled as shown in the picture below.
2. The given balloon is inflated slightly so the rubber is almost tight but not stretched, and
we then had the neck tied up, and then put inside the cup.
3. A vacuum was pulled in the container and then observed the changes in the size of the
balloon
.
Air Pressure and a balloon
The Balloon began to increase in size but then remained at a steady size because the balloon was
not properly tied off. When removed from the chamber, it immediately deflated: it had enough
pressure inside of it to maintain its shape. After the vacuum was broken, outside air pressure
quickly overwhelmed whatever residual pressure remained within the balloon, crushing the
balloon.
Activity 6: Investigating the effect of air pressure on a suction cup.
1. The provided suction cup was put on the underside of the top plate of the
chamber.
2. A vacuum was pulled in the container and recorded the observations.
The Suction cup fell at 11.5 kPa.
IV. Conclusion
In activity 1 the students were to determine whether the total force on the plates was
equal to the force of atmospheric pressure on the plates. The results obtained were unfortunately
full of errors, due to blunders with the inappropriate set up of the equipment. In activity 2 the
team was experimentally determining the force holding the plates together they found the force
to be 22lb of 97.9 N. This experiment was not subject to any major difficulties except for the fact
that the separation of the plates was very quick and abrupt.
In activity 3 measuring the vacuum pulled and observing the rate of decay using science
workshop was performed. The data was later displayed in the form of a graph. In activity 4 the
lab members were investigating the effect of air pressure on the boiling temperature of water. As
the vacuum was pulled the water went into and rolling boil. The initial temperature of the water
was 58 C and after the water boiled and the temperature was measured it went down to 43 C. In
this experiment there might have been a blunder because the team members may have stalled too
long before taking the final temperature of the water.
Activity 5 consisted of investigating the effects of air pressure on the size of the balloon.
Unfortunately, the below but that was used in the experiment was improperly tied off and so it
would lose the pressure that would build up inside however, the lab members noted that once the
chamber was opened the balloon immediately lost all its pressure inside and deflated. The
purpose of activity 6 was to investigate the effect of their pressure on a suction cup the procedure
to set up the experiment was identical to that of in activity 5. It was recorded that suction cup fell
when the pressure went to 11.5 KPa.
Overall, the lab was a total success, lots were learned about the pressure; despite the fact
that they were some errors and difficulties encountered.