Penny Drop Lab
September 24, 2016
Gia Hill, Section C
Introduction
The purpose of this lab is to design a scientific experiment
using independent and dependent variables and to vary
and debug data collection methods to achieve the best
measurement precision. How does increasing the height at
which a penny is dropped in a direct path to the ground
affect the time measured from the moment the penny is
released until the instant it makes contact with the ground?
The hypothesis is that as the height at which the penny is
dropped increases so would the time from when the penny
is dropped until the instant it hits the ground, on Earth.
Procedure and Materials
What You Will Need: pennies, stop-watches, various tools
used for measuring distance, masking tape, pen, way to
keep track of data
Before Dropping
Use the masking tape to mark and pen off 50cm, 70cm,
100cm, 120cm, and 150cm.
How to Drop the Penny
Lab Partners: S. Riley, R. Raja
Constants and Equations
𝑚𝑝 = 2.53𝑔
𝑐𝑚
𝑎𝑇 = −1400.2 2
𝑠
= −14.002 𝑚/𝑠 2
ℎ
50 𝑐𝑚, 70 𝑐𝑚, 100 𝑐𝑚,
={
}
120 𝑐𝑚, 150 𝑐𝑚
𝑡𝑎𝑣𝑔 = 0.0683ℎ0.3715
−2ℎ
𝑡𝑇 [ℎ] = √
𝑎𝑇
Data Summary
h
tavg
STDEV
(cm)
50.000
70.000
100.000
120.000
150.000
(s)
0.29
0.34
0.36
0.38
0.47
(s)
0.08
0.05
0.03
0.07
0.08
%RSD
of tavg
25.51
15.67
9.44
17.24
17.95
Avg
tT
(s)
0.50
0.59
0.71
0.77
0.87
17.16
%err
of t
41.20
42.36
49.09
50.43
46.08
Avg
tavg2
2
(s )
0.09
0.12
0.13
0.15
0.22
45.83
Graph
1. Hold the penny’s face parallel to the ground and
line the bottom up to the line marking which place
the penny is being dropped at.
2. The penny dropper should let go of the penny by
opening up the fingers wider.
3. The timer should start the timer the moment the
penny dropper’s fingers let the penny go. To ensure
this, the dropper should say “3, 2, 1, go!,” and the
timer should start it when the dropper says go.
4. The timer should stop the timer when the timer
sees the penny touch the ground.
5. The recorder should write down the time.
6. Repeat this 1-4 at the same height for nine more
times.
7. Repeat steps 1-5 for the other four heights.
Diagram
a
h, t
Average Drop Time, tavg (s)
Time vs Height
0.60
0.40
0.20
0.00
0
50
tavg = 0.0683h0.3715
R² = 0.9157
100
150
200
Height, h (cm)
Analysis
As the penny drop height increased, the average time
increased. This can be determined because the equation of
best fit. The equation best fit is a quadratic equation for this
particular set of data. When entering any positive height
into the equation, the time will increase from height below
it. There is about a 50% error bar due to human errors.
When entering any height into the equation of best fit, the
time could be found. Then when the time and distance is
entered into the tT[h] equation, the theoretical acceleration
can be found. The theoretical acceleration is not around the
approximation of gravity’s acceleration because the
regression line was not approximate.
Conclusions
The data supported the hypothesis. Something that could
be improved is how and when the timer is stopped. If done
on a harder floor, maybe the timer could be stopped when
the penny is heard hitting the floor. When calculating the
equation, the air resistance was not taken into account.