A 20 kg mass is situated 4m above the Earth's surface Taking g as 10 m/s2. What are the gravitational field strength and gravitational force acting on the mass? Am I wrong when I say that because the height of the mass ( which is 4m) is too little comparing with the radius of the Earth so that the gravitational field strength is equal to the free fall acceleration? My answer key said that not 10 but 40 is the right answer. Can anybody explain to me why the answer is 40?