Oscillations Questions and Answers Part-15

1. The ratio of frequencies of two pendulums are 2 : 3, then their length are in ratio
a) \[\sqrt{2/3}\]
b) \[\sqrt{3/2}\]
c) \[4/9\]
d) \[9/4\]

Answer: d
Explanation:
q141
q141a

2. Two pendulums begin to swing simultaneously. If the ratio of the frequency of oscillations of the two is 7 : 8, then the ratio of lengths of the two pendulums will be
a) 7 : 8
b) 8 : 7
c) 49 : 64
d) 64 : 49

Answer: d
Explanation:
q142

3. A simple pendulum hanging from the ceiling of a stationary lift has a time period \[T_{1}\] . When the lift moves downward with constant velocity, the time period is \[T_{2}\] , then
a) \[T_{2}\] is infinity
b) \[T_{2}>T_{1}\]
c) \[T_{2}< T_{1}\]
d) \[T_{2}=T_{1}\]

Answer: b
Explanation:
q143

4.If the length of a pendulum is made 9 times and mass of the bob is made 4 times then the value of time period becomes
a) 3T
b) 3/2T
c) 4 T
d) 2 T

Answer: a
Explanation:
q144

5. A simple pendulum is taken from the equator to the pole. Its period
a) Decreases
b) Increases
c) Remains the same
d) Decreases and then increases

Answer: a
Explanation:
q145

6. There is a simple pendulum hanging from the ceiling of a lift. When the lift is stand still, the time period of the pendulum is T. If the resultant acceleration becomes g / 4, then the new time period of the pendulum is
a) 0.8 T
b) 0.25 T
c) 2 T
d) 4 T

Answer: c
Explanation:
q146

7. The period of a simple pendulum measured inside a stationary lift is found to be T. If the lift starts accelerating upwards with acceleration of g / 3, then the time period of the pendulum is
a) \[\frac{T}{\sqrt{3}}\]
b) \[\frac{T}{3}\]
c) \[\frac{\sqrt{3}}{2}T\]
d) \[\sqrt{3}T\]

Answer: c
Explanation:
q147

8. Time period of a simple pendulum will be double, if we
a) Decrease the length 2 times
b) Decrease the length 4 times
c) Increase the length 2 times
d) Increase the length 4 times

Answer: c
Explanation:
q148

9. Length of a simple pendulum is l and its maximum angular displacement is \[\theta\], then its maximum K.E. is
a) \[mgl \sin\theta\]
b) \[mgl \left(1+\sin\theta\right)\]
c) \[mgl \left(1+\cos\theta\right)\]
d) \[mgl \left(1-\cos\theta\right)\]

Answer: d
Explanation:
q149

10. The velocity of simple pendulum is maximum at
a) Extremes
b) Half displacement
c) Mean position
d) Every where

Answer: c
Explanation: Mean position