NEET-XII-Physics
04: The Forces
- #9The force with which the earth attracts an object is called the weight of the object. Calculate the weight of the moon from the following data : The universal constant of gravitation G = 6.67 × 11-11 N-m2/kg2, mass of the moon = 7.36 × 1022 kg, mass of the earth = 6 × 1024 kg and the distance between the earth and the moon = 3.8 × 105 km.Ans : The force between the Earth and the Moon is given by `` F=\frac{\,\mathrm{\,G \,}Mm}{{r}^{2}}``.
Here, M is the mass of the earth; m is the mass of the moon and r is the distance between Earth and Moon.
On substituting the values, we get:
`` F=\frac{6.67\times {10}^{-11}\times 7.36\times {10}^{22}\times 6\times {10}^{24}}{3.8\times 3.8\times {10}^{16}}``
`` =\frac{6.67\times 7.36\times {10}^{35}}{(3.8{)}^{2}\times {10}^{16}}``
`` =20.3\times {10}^{19}=2.03\times {10}^{20}``
`` \approx 2.0\times {10}^{20}\,\mathrm{\,N \,}``
`` ``
∴ The weight of the moon is `` 2.0\times {10}^{20}\,\mathrm{\,N \,}``.