How does altitude affect gravitational attraction?

Altitude affects gravitational attraction by decreasing it; the higher the altitude, the weaker the gravitational pull.

Gravitational attraction is the force that draws two objects towards each other. It is governed by Newton's law of universal gravitation, which states that every particle of matter in the universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres. This means that as the distance between the objects increases (as with increasing altitude), the force of gravitational attraction decreases.

The Earth's gravitational field strength is approximately 9.81 N/kg at sea level. However, as you move away from the Earth's surface, the gravitational field strength decreases. This is because the gravitational field strength (g) is given by the formula g = GM/r^2, where G is the gravitational constant, M is the mass of the Earth, and r is the distance from the centre of the Earth. As r increases with altitude, g decreases.

For example, at an altitude of 1000 km above the Earth's surface, the gravitational field strength is only about 98% of what it is at sea level. At an altitude of 10,000 km, it's only about 25%. This decrease in gravitational attraction with altitude is why astronauts in orbit around the Earth experience weightlessness. They are still subject to Earth's gravity (in fact, it's what keeps them in orbit), but the force is much weaker than at the Earth's surface.

However, it's important to note that this decrease in gravitational attraction with altitude is relatively small unless you're at a very high altitude. For most practical purposes (like flying an aeroplane or climbing a mountain), the change in gravitational attraction with altitude is so small that it can be ignored.

In conclusion, while the effect of altitude on gravitational attraction is significant at very high altitudes, it's relatively small at the altitudes most of us experience in our daily lives. Nonetheless, it's an important concept in physics and is crucial for understanding phenomena like the orbits of satellites and the weightlessness experienced by astronauts.