Question

The second's pendulum is taken from earth to moon, to keep time period constant (a) the length of the second's pendulum should be decreased (b) the length of the second's pendulum should be increased ( c) the amplitude should increase (d) the amplitude should decrease.

Answer 1

(a) The length of the second's pendulum should be decreased.  

Exaplanation:

            TIME PERIOD OF A SIMPLE PENDULUM

The time period of a second's pendulum is given by  

       T = $\sqrt{g/L}$

Where T is the time period of simple pendulum

g is the acceleration due to gravity

L is the length of pendulum

The acceleration due to gravity of moon is 1/6 times the acceleration due to gravity of earth.  

Hence length of the pendulum should be decreased to L/6 to obtain the same time period , hence the length of the pendulum should be decreased.