Solutions

Question-3 : Tunnel in an Exoplanet!!

The exoplanet Kepler-138c has radius RK = 1.2 RE, where RE is the radius of the Earth, and density equal to that of the Earth. The inhabitants dug a tunnel straight through the centre of the planet (along the diameter). How much longer will it take to free-fall through this tunnel (without friction or propulsion) than through a similar tunnel on Earth? Give your answer in seconds. Assume that both planets are homogeneous.

Answer : 0