Question

An object has a mass of (mass) kg is on a journey from the earth to the moon. If the distance from the center of the earth to the center of the moon is 385,000 km, what is the magnitude of the net force (in Newtons) acting on the object when the object is (f) of the way to the moon?

Answer 1

Let,

m = mass of the object

M_earth = mass of the earth

M_moon = mass of the moon

f = distance of the object from the earth

d = 385000 km = distance between the earth and the moon

d - f = distance of the object from the moon

Net force on the object when it is f distance away from the earth

F_net = F_​​orce on the object due to earth - Force on the object due to moon

F_net = {GM_earthm/f²} - {GM_moon×m / (d-f)²}

Where G = 6.67×10^-11Nm²/kg²

Putting the values of M_earth , M_moon , m , d and the distance f we can find the net force.