Answer:
= 15.6 Newtons .
Step-by-step 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 .