A planet has the same size as that of the earth but its mass is 4 times the mass of the earth. What is the energy required to lift a stone of mass 5 kg vertically upwards through 3 m, on the planet ? [g on the surface of the earth `= 10 m//s^(2)`]

Options

A. 300 J
B. 350 J
C. 500 J
D. 600 J

Answer

D

Explanation

On the earth `g=(GM)/(R^(2))`
On the planet `g'(GM')/(R'^(2))` but M' = 4 M and R = R'
`therefore (g')/(g)=(G4M)/(R^(2))xx(R^(2))/(GM)=4 " " therefore g'=4g=40 m//s^(2)`
`therefore` Energy required = mgh
`= 5xx40xx3=600 J`