Question

If a planet existed whose mass was twice that of Earth and whose radius 3 time greater, how much will a 1 kg mass weigh on the planet?

Answer 1

Here,`M_(P)=2M_(e)andR_(p)=3R_(e)`
`m=1kg,W_(p)=?`
As`g_(e)=(GM_(e))/R_(e)^(2)` and `g_(p)=(GM_(P))/R_(p)^(2)`
`g_(p)/(g_(e))=M_(p)/R_(p)^(2)xxR_(e)^(2)/M_(e)=M_(p)/M^(e)xx(R_(e)/R_(p))^(2)`
`g_(p)=g_(e)xxM_(*p)/M_(e)xx(R_(e)/R_(p))^2`
or `g_(p)=9.8xx2xx(1/3)^(2)=2.17m//s_(2)`
`W_(p)=mg_(p)=1xx2.17=2.17N`