Question

A star s is being orbited by a planet p such that the planet rotates around itself once every 0.1 earth days. it is observed that p completes 196 rotations around itself by the time it completes 1 revolution around s. if the planet's sense of rotation and revolution is in same direction, its orbital period (in earth days) would be (a) 19.6 (b) 19.5 (c) 19.7 (d) 19.8

Answer 1

answer : option (a) 19.6

explanation : A star s is being orbited by a planet p such that the planet rotates around itself once every 0.1 earth days. it is observed that p completes 196 rotations around itself by the time it completes 1 revolution around s.

we know, orbital period is the time taken to to complete one revolution of orbit.

given, time taken to rotate around itself = 0.1 earth Day

there are 196 rotations around itself by the time it completes one revolution.

so, time taken to complete one revolution of orbit = number of rotation × time taken to rotate around itself

= 196 × 0.1

= 19.6 earth Day

hence, option (a) is correct choice.