Planet X has mass and radius

PHYSICS · Multi-part · A Level · Physics · Fields and their consequences · Fields and their consequences

Problem

Planet X has mass

4.0\times10^{24}\,\text{kg}

and radius

4.0\times10^{6}\,\text{m}

. Planet Y has the same average density as Planet X but a radius of

8.0\times10^{6}\,\text{m}

. (i) Calculate the acceleration due to gravity at the surface of Planet X. (Use

G = 6.67\times10^{-11}\,\text{N m}^2\!/\text{kg}^2

.) (ii) Calculate the acceleration due to gravity at the surface of Planet Y.