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.