Page 99 - Physics - XI

VIVA VOCE

Q1. Defi ne spring constant or force constant of a spring.
Ans. Force constant or spring constant is the restoring force per unit extension of the spring. If F is the
restoring force for the extension x, then force constant (k) will be
F
k =
x
Q2. What is the S.I. unit of spring constant?
Ans. N m –1

Q3. Mention the eff ect of the thickness of the wire of the spring on the value of the spring constant?
Ans. A spring of the thicker wire has more spring constant.

Q4. Is there any other way to fi nd out force constant of a spring?
Ans. By measuring the time period (T) of a loaded spring when it oscillates with the relation,
m 4π m
2
T = 2π or k =
k T 2
where K is the force constant, m is mass loaded.
Q5. What is the eff ect of length of spring on spring constant?
Ans. Spring constant decreases with an increase in the length of spring and vice-versa.

Q6. What type of motion is produced when a weight attached to the spring is slightly pulled and
then released?
Ans. The motion of the suspended weight becomes simple harmonic motion (SHM).

Q7. If two springs are identical in all respect except for the diameter of the wire of which they are
made, which one of the two springs would have more value of spring constant?
Ans. The spring which is made of thicker wire will have more value of spring constant.

Q8. How does the force constant depend upon loaded weight?
Ans. The force constant does not depend upon mass loaded.

Q9. Two springs A (Soft) and B (Stiff ), loaded with the same mass on their hangers, are suspended
one by one from the same rigid support. They are set into vertical oscillations at diff erent times,
and the time period of their oscillations are noted. In which spring will the oscillations be slower?
(NCERT)
Ans. For stiff string (B), the spring constant is more than for soft spring (A).
1
As, T ∝
k

So, the time period of oscillations will be slower in the stiff spring (B).

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