Page 58 - Physics - XI

Q3. The bob of a simple pendulum is a spherical hollow ball fi lled with water. A plugged hole near
the bottom of the oscillating bob gets suddenly unplugged. During observation till water is
coming out, the time period of oscillation would

a. remain unchanged b. increase towards a saturation value
c. fi rst increase and then decrease to the original value
d. fi rst decrease and then increase to the original value
Q4. The formula for the period of a simple pendulum is

a. T 2 l 2 b. T 2 g c. T 2 l g d. T 2 l
g l g
Q5. The graph between the length and the square of the time period of a simple pendulum is a
a. parabola b. circle c. straight line d. hyperbola

Q6. The time period of a simple pendulum depends on
a. mass of the bob b. amplitude of oscillation
c. length of the pendulum d. all of these
Q7. If a simple pendulum takes 40 seconds to complete 20 oscillations, then the time period of the
simple pendulum is

a. 2 seconds b. 0.2 second c. 5 seconds d. 0.5 second
Q8. A second's pendulum is used in the pendulum clock. The length of a second's pendulum at a
m
place where g 2 2 is
a. 2 m s b. 1 m c. 1.5 m d. 2.5 m
Q9. The length of the second's pendulum on the surface of the Earth is 1 m. The length of the same
pendulum on the surface of the moon where the acceleration due to gravity is (1/6)th of the g
on the surface of the Earth is

a. 36 m b. 1 m c. 1/36 m d. 1/6 m
Q10. Which of the following is the correct defi nition of oscillation?
a. A linear motion from one point to another b. A random back-and-forth movement
c. A repetitive to-and-fro motion about an equilibrium position
d. A circular motion around a fi xed point

Answer key

1. (b), 2. (a), 3. (a), 4. (d), 5. (c), 6. (c), 7. (a), 8. (b), 9. (d), 10. (c)

Case Study-based Questions

Read the paragraph and answer the questions that follow.
One of the most well-known periodic motions is that of a simple pendulum. A simple pendulum consists
of a small metallic ball or a piece of stone suspended from a rigid stand by a thread. The metallic ball is
called the bob of the pendulum. The to-and-fro motion of a simple pendulum is an example of a periodic
or an oscillatory motion. The pendulum is said to have completed one oscillation when its bob, starting
from its mean position moves to its extremes and back to its mean position. The pendulum also completes
one oscillation when the bob moves from one extreme position to the other extreme and comes back to

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