At what distance from the earth's surface will a mass of 50kgs be just 481 N.?

Question

find S=distance of object in the earth's surface.

Answer 1

You don't need to know G, since g=G*Me/Re^2. The acceleration at radius r = 481/50 = 9.62. Acceleration is proportional to 1/radius^2, so r/Re = sqrt(g/9.62), where earth radius Re = 6378.137 km. Thus
h = r-Re = Re*(sqrt(g/9.62)-1).
Plug in your own value of g at earth's surface (10? 9.8? 9.81? 9.80665?) and solve.

Answer 2

I'll provide the method, you can plug in the numbers

W = m*g
g = W/m

g is the acceleration due to gravity and it is defined as follows,
g = G*Me/(Re+h)^2

(Me and Re are the mass of the Earth and radius of the Earth, respectively)

solve for h

(Re +h)^2 = (G*Me)/g

h = sqrt((G*Me)/g)-Re