EXPERIMENT NO. 1
The aim of this experiment is to determine the
acceleration due to gravity using a simple pendulum. You’re provided with a
thread, pendulum bob, metre rule, cork, retort stand and a stop watch or stop
clock. Hang the pendulum bob on one end of 100-cm length of thread and clamp
the other end firmly on the retort clamp using cork. The clamp should be fixed
at the edge of the laboratory bench as shown in side and front view diagrams
below.
Pull the pendulum bob aside at a small angle so that it
swings with small amplitude. Find the time t for 20 oscillations as it swings
from point A via C to D. Repeat this procedure with the lengths of thread of 80cm,
60cm, 40cm and 20cm.
Tabulate your results including the column of period T
(second) and T2
Length L (m)
|
Time t for 20
osc (s)
|
Period T(s)
|
T2(s2)
|
1.0
|
|||
0.8
|
|||
0.6
|
|||
0.4
|
|||
0.2
|
a) Plot the graph of lengths T2(s2)
of the thread against L(m)
b) Find the slope of the graph
c) Using the relationship $$T={2π}\sqrt{l\over g}$$ Find the value of acceleration due to gravity g
d) State all possible sources
of errors in this experiment and state the precautionary measures that are to
be taken in order to reduce the effect of those errors
SOURCEES OF
ERRORS IN THE EXPERIMENT
Environmental sources
Wind resistance to the oscillating motion of a pendulum
bob
Measurement sources
i) Errors in measurement of
length which may include parallax and zero error of the measuring devices
ii) Error in timing device like
stop watches (errors in starting and stopping a stop watch)
iii) Large angle of displacement
of the bob which may disturb to and fro movement of the bob
Graphing error
i) Uses of blunt pencil in
drawing graph
ii) Too much estimation when
drawing graph
iii) Taking very close points
when calculating slopes from graph
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