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# FREE FALL 1

INTRODUCTION

AIM :
To determine the acceleration due to gravity for two similar size balls with different mass.
THEORY :
Free Fall is a common term for any motion that is determined by the act of gravitational
forces.For instance,a person in free fall experiences weightlessness. Air resistance in the earth's
atmosphere, slows down an object's rate of descent, while less-obvious attritional forces affect
the speed of orbiting objects. Any object that is being acted upon only by the force of gravity is
said to be in a state of free fall.At the same time, there are two important motion characteristics
of free-falling objects which are free falling objects do not encounter air resistance and it falls at
a constant acceleration of 9.8 m/s/s.It is because free-falling objects are accelerating downwards
at a rate of 9.8 m/s/s. If an object travels downward and speeds up, then its acceleration is
downward.
When the term object in free fall is used, this term includes the dropping as well as the
upward or downward throwing. Any object that falls freely experiences an acceleration directed
to the center of the Earth or downward, no matter the initial object movement.
Extra theory of free fall is the acceleration of a body falling freely in a vacuum near the
surface of the earth in the earth's gravitational field, the standard value is 9.806 65 metres per
second per second or can be mentioned as 32.174 feet per second per second. The symbol of g is
called acceleration due to gravity acceleration of gravity.
In addition, when an object experience free fall in a vacumm,its acceleration will be the same.
It is proved when free fall was demonstrated on the moon by astronaut David Scott on August 2,
1971 where he simultaneously released a hammer and a feather from the same height above the
moon's surface. The hammer and the feather both fell at the same rate and hit the ground at the
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same time. This demonstrated Galileo's discovery that in the absence of air resistance, all objects
experience the same acceleration due to gravity. (On the Moon, the gravitational acceleration is
much less than on Earth, approximately 1.6 m/s).
Graphs of how the acceleration ,velocity, position of objects under free fall motion change in
time follow.

## Where g = gravitational acceleration

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t = time
h = height
v = velocity

METHODOLOGY
There is an experiment been done based on the free fall theory to determine the acceleration due
to gravity for two similar size balls with different mass.
Apparatus used is Pasco free fall adapter , Pasco photogate timer , ring stand , two 90 degrees
clamps , steel and cuprum balls ( inch diameter) and a meter stick.
The setup and procedure of the experiment are as follow;

## Figure 1 : Free Falling Apparatus

1. The release mechanism is attached to a ring stand with 90 degrees as shown in figure
2.0.The clamp is positioned 90 degrees to hold the release mechanism so that the
distance between the center of a ball in the release mechanism and the center of the
ball is directly below on the receptor pad and the receptor pad is placed on the floor
directly below the release machine.The ring stand clamp is adjusted to 20.0cm from
2. The phone jack is plugged from the control box into a photogate timer.The timer is
switched on and the timer is set in GATE mode.
3. The steel ball is placed in the release machine.Then,the metal dowel pin is pressed so
that the ball is clamped between the brass contact screw and the hole in the release
plate.The receptor pad is tapped to reset the free fall electronics timer and then the
RESET button is pressed to reset the photogate timer.
4. The dowel pin is quickly released so that the balls motion is not restricted by the
release mechanism after the timer starts.
5. Then the time on the digital display of the timer is recorded.This the time it takes the
steel ball to fall to the receptor pad directly below.
6. The procedures is repeated with different height of 40.0 cm , 60.0 cm , 80.0 cm 100.0
cm.
7. The procedures and the time of fall for the cuprum ball and for the distances in
repeated and recorded respectively.

ANALYSIS
For the graph of distance against fall times for steel ball and cuprum,the motion of both graphs
shows the fall time increases with distance.The points all are not connected in a straight line,but
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a line of best fit is drawn . It minimizes the amount scatter on each graph. This clearly shows the
height which is the distance affect the fall time of the steel ball and cuprum ball.
Based on the data collected in table 1 and table 2,the speed is calculated by formula ( Distance/
Time). Below is the calculation of speed by steel ball and cuprum ball.

STEEL BALL
When distance = 20.0 cm , Fall time = 0.21 s
Speed = 20.0 cm / 0.21s
= 95.2 cm/s

## When distance = 40.0 cm , Fall time = 0.30 s

Speed = 40.0 cm / 0.30 s
= 133.3 cm/s

## When distance = 60.0 cm , Fall time = 0.33 s

Speed = 60.0 cm/ 0.33s
= 181.2 cm/s

## When distance = 80.0 cm , Fall time = 0.40 s

Speed = 80.0 cm / 0.40s
= 200.0 cm/s

CUPRUM BALL

= 100.0 cm/s

## When distance = 40.0 cm , Fall time = 0.29 s

Speed = 40.0 cm / 0.29 s
= 137.9 cm/s

## When distance = 60.0 cm , Fall time = 0.33 s

Speed = 60.0 cm/ 0.33s
= 181.2 cm/s

## When distance = 80.0 cm , Fall time = 0.40 s

Speed = 80.0 cm / 0.40s
= 200.0 cm/s

## The estimated speed is recorded in the data sheet as shown.

For the graph of speed against time for steel ball and cuprum ball, the motion of both graphs
shows the fall time increases with speed.The points all are not connected in a straight line,but a
line of best fit is drawn .It minimizes the amount scatter on each graph.In the context of onedimentional motion,the physical significance of linear velocity versus time data is the slope of
velocity is the acceleration of the object . When graphing V vs T, the slope of the curve dV/dT =
A which is acceleration. That's the physical significance.
Hence,the acceleration is estimated in the graph of speed versus time for steel ball and cuprum
ball.Gradient is drawn in the graph for a easier calculation.

## For steel ball,

Acceleration = Y2 Y1
X2 X1
= 200.0 95.2
0.40 0.21
= 551.6 cm/s/s

## For cuprum ball,

Acceleration = Y2 Y1
X2 X1
= 200.0 100.0
0.40 0.20
= 500 cm/s/s

DISCUSSION
During the experiment, the result obtained may not 100% accurate due to some errors. The
error could be due to several factors. First of all, the object which is the steel ball or the cuprum

ball wobbles (shake) as it falls down. It actually already begins to wobble at the beginning before
it even starts to fall, but these wobbles grow more often as it is falling down due to the presence
of the air resistance.Besides that.during the fall ,the ball sometimes did not fall exactly on the
receptor pad but it bumps into the pole and wire or other places.Furthermore, the times itself
sometime did not function well , it sometimes does not show the reading of the fall times,these
situation make the experiment to be repeated for a several times.Hence, the combined effect of
all these problems during the experiment cause a fluctuation of the data points.
Besides that, the magnitude of mass and radius of the steel and cuprum balls might not 100%
accurate when the measurement been done.It is because when measuring the balls on weight
measurer,the ball will roll on it,so the machine is unable to read the correct mass of the ball.At
the same time, there are some problems when reading the diameter of the balls using the vernier
carlipers.
In addition,the retort stand not high enough to measure the distance of 100.0 cm.Hence,we
have to placed a thick book under the retort stand so that the distance of 100.0 cm can be
measured.Besides that, the apparatus which is not in good condition also gives problem during
the experiment.The release plate is loose and not tight ,so is a bit difficult to fix the ball into it.At
thr same time,while we are adjusting the ball ,the timer will be start counting ,this will effect the
fall times.
Hence,there are few suggestions to improve the quality of the experiment.First of all,to avoid
air friction that will effect the acceleration of the ball,the experiment can be done in a air tight
condition such as in a vacumm.Besides that,the apparatus should be in a good condition so that
there will no error during the experiment.

CONCLUSION

In conclusion, after the lab I have understand more on free fall including the theory,formula
and the applications.Hence,this lab is proved very helpful to understand free fall.Besides that, I
have also learned that when an object falls under the influence of gravity, its velocity increases at
a regular pace and the average of this pace is known as g = 9.8.However,when an object
experience free fall in a vacumm,its acceleration will be the same. It is proved when free fall was
demonstrated on the moon by astronaut David Scott on August 2, 1971 where he simultaneously
released a hammer and a feather from the same height above the moon's surface. The hammer
and the feather both fell at the same rate and hit the ground at the same time. This demonstrated
Galileo's discovery that in the absence of air resistance, all objects experience the same
acceleration due to gravity. (On the Moon, the gravitational acceleration is much less than on
Earth, approximately 1.6 m/s).

REFERENCES

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## Sources from internet:

http://physics.kuniv.edu.kw/phys105/expt2.pdf

http://www.thefreedictionary.com/acceleration+of+free+fall

http://theory.uwinnipeg.ca/mod_tech/node17.

http://kharlbanawap6.blogspot.com/

http://www.mente.elac.org/faculty/kiledjianv/phys%20010/Lab2.pdf

http://www.sjsu.edu/faculty/beyersdorf/Phys50lab/Manual/05-EXPERIMENT%202.pdf

http://en.wikipedia.org/wiki/Free_fall

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PHYSICS 1
DAS 14103
PHYSIC FULL LAB REPORT: FREE FALL 1
NAME

## MATRIX NUMBER : AA131268

IC NUMBER

: 950322-08-5246

DATE

: 5-12-2013

LECTURER

: PN.NORBAIZURA BT NORDIN

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CONTENT

Bil.

Title

Pages

INTRODUCTION

1-4

METHODOLOGY

4-5

ANALYSIS

6 - 13

DISCUSSION

14

CONCLUSION

15

REFERENCES

16

13
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