Question

An object on the surface of the earth weighs 90 lb. at three earth radi above the surface it will weigh

Answer 1

10lb

Step-by-step explanation:

Answer 2

acceleration due to gravity on surface of earth is given as

`g = (GM)/(R^2)`

now at the surface of earth we know its value will be g = 9.8 m/s^2

it is given that we need to find the weight at height three earth radii above the surface

so we can say

`g' = (GM)/((R + 3R)^2)`

`g' = (GM)/(16R^2)`

now from above equation we can say that here the acceleration due to gravity is 1/16 times of the gravity at surface

So as we know that the weight is measured as

`W = mg`

if gravity is decreased by 1/16 times then weight will also decrease by the same factor

So weight will be measured as

`W' = (1)/(16)* 90 = 5.625 lb`

So its weight above the surface will 5.625 lb at that height