Page 55 - Physics - XI

Mass of the bob m = ___________ g
2
Mass of the bob m = ___________ g
3
Mass of the bob m = ___________ g
4
Mass of the bob m = ___________ g
5
Table for variation of T with bobs of diff erent masses (when eff ective length L is constant)

S.No. Mass of the Length from Eff ective length Time for 20 vibrations t (s)
bob top of the bob L = l' + h + r (i) (ii) Mean Time period
(g) to the point of T = t/20
suspension = l' (cm) t(s) (s)
(cm)

1. m 1 120 cm
2. m 2 120 cm

3. m 3 120 cm
4. m 4 120 cm
5. m 120 cm
5

From the above table, we observe that time period T of the simple pendulum taking bobs of diff erent
masses, keeping L constant, is approximately same.

Result
From the table, it is observed that the time period of the simple pendulum for diff erent masses of the bobs

is same (when L is constant). Hence, we can infer that time period of the simple pendulum does not depend
on the mass of the bob.

Precautions

Same as experiment 7.

Sources of Error
Same as experiment 7.

VIVA VOCE

Q1. What is an ideal simple pendulum?
Ans. An ideal simple pendulum consists of a heavy point mass suspended by a weightless and inextensible
string. It is suspended from a rigid support.

Q2. Can we realise an ideal simple pendulum?
Ans. No, the bob has some shape and weightless and inextensible string cannot be actually realised in
practice.

Q3. What is periodic motion?
Ans. Any motion that repeats itself after a fi xed interval of time is called periodic motion.

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