Question

The length of seconds pendulum is decreased by 0.3 m when shifted to Chennai from London .if at London ,g=981cm/s²
Find g at Chennai
π²=10

Answer 1

The time period of a seconds pendulum = 2s

At London, 
g = 981cm/s² = 9.81 m/s²
find the length.

$T=2 \pi \sqrt{ \frac{l}{g} } \\ \\ 2=2 \pi \sqrt{ \frac{l}{9.81} } \\ \\ \frac{1}{ \pi } = \sqrt{ \frac{l}{9.81} } \\ \\ l= \frac{9.81}{ \pi ^{2} } =\frac{9.81}{10}=0.981m$

At Chennai,
length is 0.3 cm less or 0.003m less
so l = 0.981-0.003 = 0.978m
g = ?

$T=2 \pi \sqrt{ \frac{l}{g} } \\ \\ 2=2 \pi \sqrt{ \frac{0.978}{g} } \\ \\ \frac{1}{ \pi } = \sqrt{ \frac{0.978}{g} } \\ \\ g= 0.978* \pi ^{2} =9.78\ m/s^2=978\ cm/s^2$

So The value of g at Chennai is 978 cm/s².

Answer 2

The time period of a seconds pendulum = 2s

At London, 

g = 981cm/s² = 9.81 m/s²

find the length.

At Chennai,

length is 0.3 cm less or 0.003m less

so l = 0.981-0.003 = 0.978m

g = ?

So The value of g at Chennai is 978 cm/s².

Thanks