UNIVERSITY OF SCIENCE AND TECHNOLOGY OF SOUTHERN PHILIPPINES
College of Science and Mathematics
DEPARTMENT OF PHYSICS
PHYS120|PHYS101 – PHYSICS FOR ENGINEERS
I.
Data and Results:
Name
:
Joseph Nell Francis P.
Ligutom
Subject and Section Code
:
PHYS120 – 1M
I.D. Number
:
2020305814
Instructor’s Name
:
Lady Jaharah
Bulayog
Course & Year
:
BSCE & 1yr
Score (For Instructor Only)
:
Part A. Density Measurement of Solid and Liquid Materials
Material
Mass
(g)
Aluminum Cube
Iron Cube
44.6
53.9
Table 4.1
Density of Solid Materials
Side Length Measurement (mm)
Density (g/cm3)
Percent
Volume
Error
Main
Vernier
Final
(cm3)
Experimental Standard
(%)
Scale
Scale
Reading
25
19
35
0
25.7
19
16.97
6.86
2.63
7.86
2.70
7.80
2.59
0.77
Table 4.2
Density of Liquid Materials
Material
Water
Alcohol
Brine
Mass (g)
Pycnometer Pycnometer w/ Liquid Liquid
15
15
14.4
40.5
37.5
40
25.5
25.5
25.6
Volume
(cm3)
25
25
25
Density (g/cm3)
Experimental Standard
1.02
0.90
1.024
1.00
0.885
1.015
Percent
Error (%)
2.00
1.69
0.89
Part B. Archimedes’ Principle of Buoyancy
Table 4.3
Buoyancy of Liquids on Aluminum Cube
Weight of Cube (N):
Liquids
Water
Alcohol
Brine
44
Mass (g)
Catch Basin Catch Basin w/ Liquid
21.9
38.4
36.3
42
Liquid
16.5
14.4
23.1
Tension (N)
0.2776
0.2878
0.2725
Buoyant Force (N)
Standard Experimental
0.1666
0.1474
0.1690
0.1624
0.1522
0.1675
Percent
Error (%)
2.52
3.26
0.89
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Table 4.4
Buoyancy of Liquids on Iron Cube
Weight of Cube (N):
Liquids
Water
Alcohol
Brine
II.
53
Mass (g)
Catch Basin Catch Basin w/ Liquid
22.1
28.3
28.2
30.6
Liquid
6.2
6.1
8.5
Tension (N)
0.4674
0.4674
0.4571
Buoyant Force (N)
Standard Experimental
0.0672
0.0595
0.0682
0.0626
0.0626
0.0729
Percent
Error (%)
6.85
5.21
6.89
Computations:
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III. Discussion of Results:
In this lab experiment we attained the objectives by getting the density of a liquid and solid
material, determine the buoyant force of different materials and determine the effect of density
to the buoyancy of a material.
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First in Table 5.1, we were able to identify the density of the solid materials such as the
aluminum and iron cube. The masses were given the procedure, afterwards, we were able to
read their length measurements in mm by reading through a Vernier caliper scale. The final
readings could be computed by using the formula: main scale + (Vernier scale × 0.02mm).
Volume in each solid were computed by converting the final readings to cm3 simply by multiplying
it to 0.1 and then raised the value to its 3rd exponent. The density is computed by ; next is to
compare it to its standard density and lastly determine its percentage error.
In table 5.2, it discussed about the density of liquid materials of the following: water, alcohol
and brine. Masses were computed as well as the volume, density and percentage error. The
following results still can be seen in the said table.
For part B, in tables 5.3 and 5.4, shows the buoyancy of liquids depending to the volume of
the following solids: Aluminum and Iron. Same process have been used by computing different
factors: mass, tension, buoyant force and percentage error. The difference in here is that the
standard buoyant force has more specific formula as shown in the computations. Nevertheless,
it tells us according to the results that buoyant force using the aluminum cube’s volume is greater
compared to iron.
IV. Conclusion:
In this experiment, I can conclude that there is an existing relationship between the weight
of water displaced by an object and the buoyant force exerted on the object. It can also be
imply that the density of an object or fluid is a factor to determine whether a certain object will
either float or sink when submerged by a liquid. The activity shows that buoyant force is
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greater for heavier objects; if the object is denser than the fluid, it can entail a downward
acceleration which means to sink. In opposite, if the object is less dense, it will float or rise.
V.
Answers to Questions:
1. Consider the solid and liquid materials used in the activity. If each material has equal volume of 1 cm 3, which
material weighs the heaviest? the lightest? Arrange the materials in order of increasing mass. How does their
densities affect their masses for a given equal volume?
The density is directly proportional with their masses for a given equal volume; greater
density= heavier mass of material. So from the activity, the order of materials from lowest
to heaviest are the following: Alcohol (0.885g), water (1.00 g), Brine (1.015g), Aluminum
(2.70 g), lastly the heaviest is Iron (7.80g).
2.
Consider the solid and liquid materials used in the activity. If each material has equal mass of 1 kg, which
material occupies more space? less space? Arrange the materials in order of decreasing volume. How does
their densities affect their volumes for a given equal mass?
The density is inversely proportional with their volume for a given mass; the greater the
density, the volume of the material will be lesser. This is according to the decreasing order
of volume of the materials used in the activity.
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3.
Which liquid exerts more buoyant force on each cube? Does the density of liquids affect the buoyant force
exerted on the cube? Explain.
It is Brine that exerts more buoyant force on each cube. It has the greatest density
which means that density is directly proportional to the buoyant force that the liquid exerts
on cube. Since it has greater density, means the buoyant force exerted on the cube is also
greater.
4.
What is the relationship between the weight of the collected liquid to the weight of the object in air?
In this case, the buoyant force on a body floating in a liquid or gas is also equivalent in magnitude
to the weight of the floating object and is opposite in direction; means that the object neither rises or
sinks.
Hence, weight of displaced portion of the fluid is equivalent to the magnitude of the buoyant force.
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5.
Why is it easier to piggyback someone when you’re in swimming pool or sea as compared when you do it
with just the surrounding air?
This is because things appear lighter when you piggyback someone in the water because
the fluid is actually helping to push it up. This is also in relation to Archimedes’ principle
stating that force pushing on an object underwater is equal to the mass of the water it has
pushed out of the way. In addition, since air is less dense than water, the buoyant force of
air is less than that of water, means that object will be heavier. Thus, it will be easier to
piggyback someone in the water than in the surrounding air.
6.
Would it be easier to swim it sea than in river? Explain why.
No; due to high content of salt in the sea water, the density of the sea water is higher
compared to river water. From the data above, we can support our answer because the
density is directly proportional to buoyant force. Therefore, since sea water is denser that
the river water, the buoyant force is higher in the sea water compared to the river. Making
it easier to swim in river water than sea water. Thus, it will not be easier to swim in the sea
compared in the river.
7.
For an object that is just dropped on a liquid, how does both the density of the object and liquid determine
whether the object floats, sinks or just submerged under the surface of the liquid?
If the density of the object is greater than the liquid, then the object sinks in the liquid.
Otherwise, if the object is less dense than the liquid, then the object floats on the liquid.
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8.
Does a floating object sink more in a liquid with low density than in a liquid with high density? Explain your
answer.
Depending on the weight of the floating object; If the liquid is denser, thus the buoyant
force is greater than the object’s weight, means it will float. Otherwise if the liquid is less
dense, thus the buoyant force is less than the mass of the object, in this case, the object will
most likely to sink. Thus, the floating object would sink more in a liquid with less density
than with the high density liquid.
9.
From your data on the mass of the collected liquid in Table 5.3 and 5.4, will the volume of collected liquids
match the volume of the cubes as recorded in Table 5.1? Show some calculations to prove or disprove.
The volumes might not be close enough match; in table 5.3 for the aluminum cube
with a volume of16.97��3, the masses of the corresponding displaced liquids are: 16.5 g
(water), 14.4 g (alcohol), and 20.1 g (Brine). Converting mass into volume we just easily
change the grams to cubic centimeters since1� = 1��3. In this sense, the volume of the
displaced liquid will be close to the volume of the aluminum cube.
Another proof is that in table 5.4 for the Iron cube with a volume of6.86��3, the
masses of the corresponding displaced liquids are 6.2 g (water), 6.1 g (alcohol) and 8.5
(brine). Converting mass into volume we just simply change the grams to cubic centimeters
again, since1� = 1��3. Thus, the volume of the displaced liquid is close to the volume of
the iron cube.
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