Question

NTSE physics question Given that there is a relationship between the orbital radius of a planet and its period of revolution and that the periods of revolution of Mercury, Earth, Jupiter and Neptune are nearly 0.24, 1, 11.8 and 165 years. It follows that the period of revolution of a. Venus is less than 0.24 year b. Mars is less than 12 years c. Uranus is more than 165 years d. Uranus is less than 165 years but more than 12years Of these the correct statements are: 1. a and c 2. d only 3. c only 4. b and d Please explain! Thanks

Answer 1

T^2 varies as  R^3, where R is the distance from Sun.  So as R increases, T increases.

Planets are arranged in the increasing order of distance as:
       Mercury,  Mars, Earth, Venus,  Jupiter,   Uranus,  Neptune

so Venus - will have higher than that of Earth, > 1 year.

Mars will have less than 1 year.  so it will be less than 12 years.(of Jupiter)

Uranus will have less than 162 years and more than 12 years (that of Jupiter)


So answer is  b  and d  both.