The time periods of two simple pendulums at a place are in the ratio 2:1. What will be the ratio of their lengths ?

It takes 0.2s for a pendulum bob to move from mean position to one end. What is the time period of pendulum?

Assertion (A) : The unit used to measure speed is an example of a derived unit.

Reason (R) : Derived units can neither be changed nor can be related to any other fundamental unit.

1. both A and R are true and R is the correct explanation of A
2. both A and R are true and R is not the correct explanation of A
3. assertion is false but reason is true
4. assertion is true but reason is false

Assertion (A) : Smaller the least count of an instrument, more precise the measurement made by using it.

Reason (R) : Least count of an instrument is the smallest measurement that can be taken accurately with it.

1. both A and R are true and R is the correct explanation of A
2. both A and R are true and R is not the correct explanation of A
3. assertion is false but reason is true
4. assertion is true but reason is false