Page 56 - Physics - XI

Q4. What is the time period of a vibrating object?
Ans. The time taken to complete one vibration is called time period (f) of a vibrating object.

Q5. What is the frequency of a vibrating body?
Ans. Total number of vibrations completed in one second is called the frequency of a vibrating body.
Q6. What do you mean by the term amplitude?
Ans. The maximum distance of a vibrating body from its mean position is called amplitude.

Q7. What is the relation between time period (T ) and frequency (f ) of a vibrating body?
1
Ans. T = f

Q8. What is the time period of the simple pendulum?

L
Ans. T 2
g
Here L is the length of pendulum and g is the acceleration due to gravity.

Q9. What do you mean by damping?
Ans. It is the opposition to free vibrations of the bob of a simple pendulum due to the presence of air or
any medium around it.

Q10. Why wall clock runs fast in winter?
L
Ans. During winter the length of the pendulum decreases, so its time period T 2 also decreases.

Hence, it runs fast during winter. g
Q11. What is a second's pendulum?
Ans. A simple pendulum whose period is two seconds is called a second's pendulum.

Q12. What is the length of a second's pendulum?
Ans. The length of a second's pendulum is approximately 100 cm.
Q13. What is the length of the pendulum?
Ans. It is the distance from the point of suspension to the centre of gravity of the bob.

Q14. What type of motion does a simple pendulum execute?
Ans. It executes simple harmonic motion (S.H.M.).

Q15. What do you mean by S.H.M.?
Ans. It is defi ned as the motion of a vibrating body in which the acceleration of the vibrating body is
directly proportional to its displacement from the mean position and is always directed towards the
mean position.

Q16. Is S.H.M. a periodic motion?
Ans. Yes

Q17. Does a wall clock gain or lose time in summer?
Ans. It loses time in summer because its time period increases due to increase of length of the pendulum.

Q18. Why does the amplitude of the simple pendulum decrease after sometime?
Ans. Due to the resistance of the air and friction at the point of suspension.

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