Gravitation Ques 2

2. The time period of a geostationary satellite is $24 h$, at a height $6 R_E\left(R_E\right.$ is radius of earth) from surface of earth. The time period of another satellite whose height is $2.5 \mathrm{R}_{\mathrm{E}}$ from surface will be,

[NEET Odisha 2019]

(a) $\frac{12}{2.5}$ $ h$

(b) $6 \sqrt{2}$ $ h$

(c) $12 \sqrt{2}$ $ h$

(d) $\frac{24}{2.5}$ $ h$

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Answer:

Correct Answer: 2.(b)

Solution: (b) $T^2 \propto r^3$

$T^2 \propto\left(R_E+h\right)^3$

$\frac{T_1^2}{T_2^2} =\frac{\left(R_E+6 R_E\right)^3}{\left(R_E+2.5 R_E\right)^3}$

$\frac{T_1^2}{T_2^2} =\frac{7^3}{\left(\frac{7}{2}\right)^3}$

$T_2 =6 \sqrt{2}$ $ h$