What will be the escape speed from a planet having mass 8 times that of earth and diameter 4 times that of the earth ? `[v_(e)=11.2 km//s]`

Explanation

`v_(p) = ?`
Now, `v=sqrt((2GM)/(R ))`
`therefore (v_(p))/(v_(e))=sqrt((M_(p))/(M_(e))xx(R_(e))/(R_(p)))=sqrt((8M_(e))/(M_(e))xx(R_(e))/(4R_(e)))`
`therefore v_(p)=sqrt(2)v_(e)`
`=sqrt(2)xx11.2`
`=15.84 km//s` .