Calculate the gravitational force acting on the Moon, caused by the Earth, given that the masses of the Earth and the Moon are 6 x10^24 and 7.3 x10^22, respectively. The distance between the Earth and the Moon is 384 400 km.

The relevant equation to use in solving this problem, from Newton's law of gravitation, is Force = ( universal constant of gravitation x mass of earth x mass of moon)/ (distance between earth and moon squared), or F = Gm_Earthm_Moon/r ².The first step would be to ensure all units for the data provided are in SI units of metres (distances) and kilograms (mass). The distance is stated in km, so this will need to be changed to 3.844 x10⁸ m. The masses are already in kg so are fine to use as given. Then, the numbers get put into the equation as follows; F = (6.67 x10^-11 x 6 x10²⁴ x 7.3 x10²²)/(3.844 x10⁸)²= 1.98 x 10²⁰ Newtons, N. (making sure to use the correct unit for force, which comes about when all SI units are used in equation.