Physics problem help (gravitational forces)?

By Newton, F = GmM / d²

Here, d = 8.7e6m + 2.175e6m = 10.875e6 m

The planet's mass M = ρV = ρ*(4π/3)r³

M = 4200kg/m³ * (4π/3) * (2.175e6m)³ = 1.81e23 kg

so

F = 6.674e−11N·m²/kg² * 3870kg * 1.81e23kg / (10.875e6m)²

F = 395 N

Hope this helps!

Fg = G * M * m ÷ d^2

d = radius of planet + altitude

r = 2175 * 1000 = 2.175 * 10^6 meters

d = 2.175 * 10^6 + 8700 = 2.1837 * 10^6

To determine the mass of the planet, multiply its volume by its density.

Volume = 4/3 * π * r^3

Volume = 4/3 * π * (2.175 * 10^6)^3

The volume is approximately 4.31 * 10^19 m^3. Let’s convert the density to kg/m^3.

1kg = 1000 g

1 m = 100 cm

1 m^3 = 1 * 10^6 cm^3

1 kg/m^3 = 1000 ÷ 1 * 10^6 = 0.001 g/cm^3

Density = 4.2 ÷ 0.001 = 4200 kg/m^3

Mass = 4/3 * π * (2.175 * 10^6)^3 * 4200 = 1.8101546664 * 10^23 kg

Fg = 6.67 * 10^-11 * 1.8101546664 * 10^23 * 3870 ÷ (2.1837 * 10^6)^2

This is approximately 9800 N.