1. The problem statement, all variables and given/known data density, ρ of the rock is 4000 kg m−3 and that this density is uniform throughout. You have equipment that enables you to measure the time it takes for a small object to fall from rest through a distance of 2.00 m. Your measurement is 8.0 s. Obtain an expression for ga in terms of the gravitational constant G, the radius of the asteroid Ra and the density ρ of the asteroid. Hence determine Ra. 2. Relevant equations F= Gm/ r2 F=mg volume of sphere= 4/3 * pi * r^3 density= m/v 3. The attempt at a solution substituting volume of sphere= 4/3 * pi * r^3 into density= m/v gives- density= 3m/ ( 4* pi * r^3 ) 4/3 * pi * r^3 * density = m F= Gm/ r2 F= (G*4/3 * pi * r^3 * density) / r^2 F=G*4/3 * pi * r * density F=mg mg= G*4/3 * pi * r * density 4/3 * pi * r^3 * density = m 4/3 * pi * r^3 * density* g = G*4/3 * pi * r * density g= Gr^-2 or g= G / r^2 (is this correct)???