The time period of a simple pendulum at the surface of the earth is T. If it is taken to a height of 640 km, its time period will

Options

A. increase by 20%
B. increase by 10%
C. decrease by 10%
D. decrease by 5%

Answer

B

Explanation

`g_(h)=g((R)/(R+h))^(2)`
`=g((640)/(6400+6400))^(2)`
`=g((100)/(121))`
`T'=(11)/(10)T`
`(T'-T)/(T)xx100=10%`.