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European Journal of Applied Sciences – Vol. 9, No. 4
Publication Date: August 25, 2021
DOI:10.14738/aivp.94.10446. Sharma, O., & Sharma, D. (2021). How Free is a Fall That Occurs in Real World?. European Journal of Applied Sciences, 9(4). 39-53.
Services for Science and Education – United Kingdom
How Free is a Fall That Occurs in Real World?
Om Sharma
Natick High school, Natick, MA 01760, USA
Dipti Sharma PhD
Emmanuel College, Boston, MA 02115, USA
ABSTRACT
Observing a rain fall or falling leaves or tossing pizza dough in air, can give some
thought of free fall. But how free are they? These types of questions can come to
anyone’s mind when you see something falling in air to the ground. What is a free
fall and how is different than not being a free fall? In my present research, I studied
and tested concepts of free fall using various types of objects those are different in
shape, size, weight, and volume. I tested them for free fall by dropping them from
same height to find out how accurately they follow free fall conditions or if they do
not follow free fall theory then what are the causes. Is there any experimental error
that is causing a fall not to be a free fall, or it is natural or something else? I also
tested how weight and height can affect free fall of objects. After experiments, it
came out that objects those are very light in weight or very large in volume or have
ability to hold air in it due to their shape show deviation from free fall concepts and
counted as non-free fall objects.
INTRODUCTION
In everyday life, we see various falls which can be a rock
falling from a top of the hill as shown in the Image 1 or a ball
falling from the balcony of the 2nd floor, or a toy fell from a
table or a bird feather or a hair is falling to the ground. Based
on how large or small object is or how light or heavy object
is or how much air object can hold, the fall can be affected.
In this research, our goal is to find out the falls we usually
see in our daily life and determine if they are free fall or not.
If not, then why not. To understand the depth of the concept
of whether a fall is free or not, we used different steps and
methods to follow, and they are given below. We tested how
time of the free fall is affected by the type, shape, size,
weight of the object, and how the height of the fall plays role
in free fall. Whether all falls we see in real world those
occurs in everyday life are free fall or not. Is there any
simpler way to measure and detect if falls are free or not
without going to a tedious laboratory and performing
experiments at home or school?
Image 1: Cartoon
depicting a free fall in the
real life. [1]
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European Journal of Applied Sciences (EJAS) Vol. 9, Issue 4, August-2021
Services for Science and Education – United Kingdom
Our interest is to determine which objects appear to be close enough to free falling over
relatively short distances such as within a household setting using household objects those are
different in shapes, size, weight and dropped from different heights. Which objects would show
higher value of air resistance and how this air resistance can be measured in simpler way?
What is a Free Fall?
Any fall that occurs under the influence of gravity solely is called free fall. That means if we look
free body diagram (FBD) of an object, it should have one downward force which is gravity (Fg)
only. If we happen to measure the gravity under which object is falling, and if it comes as gravity
of Earth as 9.81 m/s^2, it means the fall is free fall. Free fall doesn’t show any other additional
force acting on the object other than force of gravity. It is said that in Vacuum, objects in free
fall, accelerates with same rate regardless of their mass. [2]
What is not a Free Fall?
Any object that falls has more than one force acting on it which is additional force than force of
gravity is called non-free fall. In other words, if the gravity under which object is falling is
calculated or found by performing experiments and if it comes different than g = 9.81 m/s^2 on
Earth, it means fall is not a free fall. It is possible the calculated gravity for a particular fall comes
either larger or smaller than 9.81 m/s^2 and it shows clear indication of either an additional
force that supporting gravity or opposing gravity. Some examples can be used as windy
weather, warm weather, or presence of air resistance. If object has an opposite force upward
force because of air in addition to its gravitational force, it is called that object has air resistance
and not falling under free fall.
Based on types of fall, object may take different time of fall indicating that whether it is a free
fall or non-free fall. Our goal is to test free fall with multiple types of objects those are available
at everyone’s home and we use them in our daily life. They are different in shape, size, and
weight and whether they show free fall or not and if not then why not.
Research Questions, Hypothesis and Variables
During these experiments, these questions are tested to find whether fall is a free fall or not. 1)
How free can a fall be that occurs in real world? 2) How long does an object take to fall from a
given height to the ground? 3) How the time of fall is affected by the shape of object if dropped
from the same height, 4) What would be its velocity when it hits the ground? 4) Can shape, size
and weight of an object change its data of free fall? 5) What applications can be seen of free fall
in real world?
Before beginning experiments, the hypothesis for the experiments is: 1) Heavier object will take
less time to fall than lighter object, 2) Different shape and size objects will take different time
to fall, 3) Objects will hit ground with their highest speed, 4) Higher the height, longer the time
of fall, 5) A general free fall may show presence of air resistance. 6) Are there simple ways of
performing experiments at home or school to see how air resistance affect free fall?
The variables used in the experiments of free fall are: Independent Variables were Height and
Objects. Dependent Variables were Time, Velocity, Force and Acceleration. Controlled Variables
were Gravity, Number of repetitions, Experimental condition, Temperature and Humidity.
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Sharma, O., & Sharma, D. (2021). How Free is a Fall That Occurs in Real World?. European Journal of Applied Sciences, 9(4). 39-53.
URL: http://dx.doi.org/10.14738/aivp.94.10446
To understand the affect of free fall or air resistance, some modified version of Physics
equations are used and tried to find simple equations to see if they can show affect of air
resistance in various objects or not. The presence of air resistance shows an upward force on
the object and reduces the amount of gravitational force. It can be said that there is drag force
that makes object to fall slower than usual based on objects shape and size or ability to hold air.
Details concepts and equations are discussed in the result and discussion section of this paper.
Materials: Materials used for free fall experiment and data collection
Following objects are used for these experiments those are available to anyone’s home:
Basketball, Soccer Ball, Dodgeball, Tennis Ball, Golf Ball, Bouncy ball, Marble, Paper ball,
Wooden block, Wooden block with a hole, Pencil, Feather, Balloon w/o air, Thick Book, Bracelet,
Balloon with air, Shoe, Plain paper, Pillow, Metallic Bowl, Closed umbrella, Duckie toy, Plastic
bowl, Open umbrella, Foam cup, Paper sticker, Coffee closed cup, Paper bookmark. Notebook,
Laptop, Pencil, Microsoft Office, calculator, Stopwatch, Tracker Data Analysis Software, Phone
and Meterstick.
METHODS AND THEORIES
To perform experiments with household objects, following methods and steps are used.
1.Objects were weighed using a digital balance. 2. Objects were dropped from a height of 2
meters and time of fall was recorded using Three Methods: a) Stopwatch, b) Cellphone, c) Video
Analysis (using Tracker video analysis software). 3. Each experiment was repeated five times for
accuracy. 4. 29 non-breakable objects were dropped from 2 m height. 5. To avoid air resistance,
experiments were performed inside house in same environmental conditions with room
temperature at 70 oF and normal humidity of 33%. [3] A device is used to find temperature and
humidity of the room where experiment was performed, and the room temperature and
humidity were kept identical for entire experiments. 6. Using equations of Free fall, theoretical
time of fall and final velocity of objects were calculated and compared with experimental values.
7. The possible causes of errors were considered, 1) reaction time, 2) air resistance. 8.Some
objects were dropped from 1 m of height to see difference between heights of falls.
Initially, first two objects, a basketball and a wooden block were chosen first to drop from a
height of 2 m and the time of fall was recorded with three different methods, 1) time from
manual stopwatch as Ts, 2) time from cellphone as Tp, and 3) time from tracker video analysis
as Tv. To find out what method of measuring time of fall is better, these three methods of time
of fall were compared. To get the time of fall, the object was placed at the height of 2 m and then
released, and time was recorded of object’s fall until it hits the ground. This time is called Texp.
This time was recorded using three methods as described above. Each object was dropped for
five times and then time data was collected and then average of the Texp is found. The Texp
was found with stopwatch, phone, and video analysis. The stopwatch and phone used user’s
finger to be clicked so reaction time factor can be involved in these two methods but when Texp
was recorded by video analysis, no reaction time factor is found in this method as time was
obtained by clicking time button.
To see what the most effective way is to find Texp, the time of the fall recorded as Ts, Tp and
Tv, they are compared. When difference between Ts and Tp were calculated, it came almost
zero which means no matter if use manual stopwatch or phone as watch, they were same. The