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Question : 15 of 25
Marks: +1, -0
The acceleration due to gravity on the surface of moon is 1.7 m s−21.7\,\text{m s}^{-2}. What is the time period of a simple pendulum on the surface of moon if its time period on the surface of earth is 3.5 s? (g on the surface of earth is 9.8 m s−2)9.8\,\text{m s}^{-2})
Solution:  
Using the formula T=2Ï€lg,T=2\pi\sqrt{\frac{l}{g}}, we get
For earth Te=2πlge,…(i)T_{e}=2\pi\sqrt{\frac{l}{g_{e}}},\dots(i)
and for moon, Tm=2πlgm…(ii)T_{m}=2\pi\sqrt{\frac{l}{g_{m}}}\dots(ii)
Dividing (ii) by (i), we get
TmTe=gegm=9.81.7\frac{T_{m}}{T_{e}}=\sqrt{\frac{g_{e}}{g_{m}}}=\sqrt{\frac{9.8}{1.7}}
or Tm=3.5×9817T_{m}=3.5\times\sqrt{\frac{98}{17}}
=3.55.7647=3.5\sqrt{5.7647}
=3.5×2.4=3.5\times2.4 or Tm=8.4 sT_{m}=8.4\,\text{s}
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