# The length of the string of a simple pendulum is 102.6 cm and the diameter of the bob is 2.56 cm. What is the effective length of the simple pendulum

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The length of the string of a simple pendulum is 102.6 cm and the diameter of the bob is 2.56 cm. What is the effective length of the simple pendulum by using the correct number of significant figures? (Rounding off is not to be considered.)
A. 103 cm
B. 103.88 cm
C. 103.8 cm
D. 103.9 cm

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The effective length of the simple pendulum
= Length of the string + radius of the bob
=102.6cm+(2.56)/(2)cm
therefore L=102.6+1.28=103.88cm
But in addition and subtraction, the result should have the minimum number of decimal places, which are present in the added quantities. In this case, 102.6 cm has only one decimal figure.
therefore The effective length of the simple pendulum, by using correct number of significant figures is 103.8 cm.
[Note : If we use rounding off method, then the answer will be 103.9.]
[0.88 is rounded off to 0.9]