Atwood
Machine
mm/dd/201L
Experiment:
Apparatus:
Atwood's
machine consisting
of
one
pulley
with
string
attached
over
pulley to two
weight
hangers;
sets
of
gramweights, meter
stick
and
stopwatch.
Procedure:
Two
experimental procedures
will
be
conducted
here.
(A)
Increasing
total
mass:
Same
amount
of
mass
is
added
to
each
weight
hanger.
Experiment
will
be
repeated
five
times, recording times
of
fall
for
each
set
of
masses.
(B)
Increasing
mass
difference
(keep
total
mass
the
same):
Move
masses
from
one side
to
the other
and repeat
measwement
five
times, recording times
of
fall
for
each
set
of
masses.
Data/Results:
y
=
B0cm
=0.BOm
Equations:
a.

[[mzmrJ/
(mr+m2)]g
a^=
2y/t2
o/o
ertor
=
(lacaml/a.J
x
100
1.
Increasing
mass
sum
m1
m2
Ac
t
dm
o/o
€
rfor
7Op
90s
L.22m/s2
L.15
s
L.ZLw/sz
0.820/o
90
s,
110
s
0.98m/s2
L.29
s
0.96m/sz
2.04o/o
110
e
130
e
0.81m/sz
1.39
s
0.83m/s2
2.47o/o
130
s
L50
s
0.70m/sz
1.55
s
0.67m/s2
4.29o/o
150 s
I70
s
0.61m/s2
1.80
s
0.49m/s2
L9.7o/o
2.
Increasing
mass
difference
m1
mz
€
lc
T
€
Im
%o
error
150
s
L70
s.
0.6Tm/s2
1.50
s
0.7Lmls2
16.4o/o
130
e
L90
e
L.B4m/s2
0.92
s
L.89m/s2
2.77o/o
1I0
s
210 s
3.06m/s2
0.72
s
3.08m/s2
0.650/o
90s
230
p
4.29m/s2
0.63
s
4.03m/s2
6.060/o
70p
250 s
5.51m/s2
0.53
s
5.70m/sz
3.44o/o
4
Lab
3:
Atwood
Machine
mm/dd/20L1,
Data
Analysis:
In
the
first
experiment
set,
it
became
apparent that
as
the
mass
was increased on
both
sides
with
the
same mass
difference,
it
took the heavier
side
longer
to
touch
the
ground,
and
the
acceleration is
increasing.
This
is
as
expected.
From the
equatioll,
dq
=
[(mzmrJ/
(mr+mz)]g,
the denominator
is increasing and
the
numerator
is
constant
therefore acceleration
is
increasing.
If acceleration
is
increasing
the
measured
fall time must
decrease
from the
equation,
a^= 2y/t2.
In
the
second
experiment, we found that
an
increasing
difference
between the
weights
shortened
the
time considerably.
As
discussed
above
this
is
as
expected
from the
equations,
a.

[(mzmt)/
(mr+mzJ]g and
a=2y/t2
In
both experiments the
%o
error
calculations
range
from about
Lo/o
to
20010,
with
the
highest
%o
errors for the
smallest values of acceleration.
The
absolute difference
between
each
set of
values
a.
and
am
is
fairly
consistent.
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