10. Gravitation – Class 9 Science | NCERT Chapter-wise Important Questions and Answers (CBSE)

Chapter 10: Gravitation – Class 9 Science NCERT | Chapterwise Important Questions and Answers (CBSE)

Chapter 10: Gravitation

Example 10.1:  The mass of the earth is   kg and that of the moon is  . If the distance between the earth and the moon is   km, calculate the force exerted by the earth on the moon. (Take G =  )

Solution: The mass of the earth, M =6×1024 kg

The mass of the moon, m =7.4×1022  kg

The distance between the earth and the moon, d =3.84×105 km

=3.84×105×1000 m

 =3.84×108 m

G =6.7×10-11Nm²kg-2

The force exerted by the earth on the moon is

F=G M × md2

=GMmd2

= 6.7×10-11Nm²kg-2×6×1024kg×7.4×1022 kg (3.84×108)2

=6.7×6×7.4×103514.75×1016

=297.4814.75×1019

 =20.16×1019

=2.02×1020N

Thus, the force exerted by the earth on the moon is 2.02×1020N .

1. State the universal law of gravitation.

Answer: The law of gravitation states that the force of attraction between any two objects is proportional to the product of their masses and inversely proportional to the square of the distance between them.

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Posted 4 months ago