Two planets have the same surface gravity, but planet b has twice the radius of planet

a. if planet a has mass m, what is the mass of planet b?

a. m/

b. m

c. m

d. 4m

e. m/4

The formula for the acceleration due to gravity is:

a = Gm/r²

where

G is the universal gravitational constant = 6.6726 x 10⁻¹¹ N-m²/kg²

m is the mass of planet

r is the radius of planet

So, if they have the same a:

m₁/r₁² = m₂/r₂²

So, if m₁ = m and r₂ = 2r₁,

m/r₁² = m₂ / (2r₁) ²

m₂ = 4m

Thus, the answer is D.