If the 40 kg boy were in a spacecraft 5.0r from the center of the earth, what would his weight be?

 =  15.6 Newtons .

Explanation:

The acceleration of gravity is proportional to the reciprocal of the square of the distance from the center.

On the surface we are 1 radius from the center of the Earth,

and the acceleration of gravity is  9.8 m/s² .

The boy's weight on earth surface = (mass) · (gravity) = (40kg) × (9.8 m/s²)

                                                            =  392 newtons.

On the other hand; At the distance of 5 radii from the center (4 radii altitude from the surface),

the acceleration of gravity is;

                (9.8 m/s²) × (1/5)²  =  0.39 m/s² .

Therefore;

The boy's weight = (mass) × (gravity)  

                             =  40 kg × 0.39 m/s²

                             =  15.6 Newtons .

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