Physics
Grade-9
Easy

Question

Two simple pendulums of lengths 5 m and 20 m respectively are given small linear displacement in one direction at the same time. They will again be in the phase when the pendulum of shorter length has completed .... oscillations.

  1. 3
  2. 5
  3. 2
  4. 1

Hint:

T equals 2 pi square root of l over g end root

The correct answer is: 2


    It is given that,
    Length of first pendulum, l1​=5m
    Length of second pendulum,l2​=20m
    Time period is given by: T equals 2 pi square root of l over g end root
    So T1=
    2 pi square root of fraction numerator l 1 over denominator g end fraction end root equals 2 pi square root of 5 over 10 end root equals 2 pi square root of 1 half end root
a l s o space 2 pi square root of fraction numerator l 2 over denominator g end fraction end root equals 2 pi square root of 20 over 10 end root equals 2 pi square root of 2
s o space T 1 equals square root of 2 space pi
T 2 equals 2 square root of 2 pi
T 2 space ​ space space equals 2 T 1 ​ space space space space T h e space v a l u e space o f space n space i s space 2

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