When can an object be considered weightless but still have a gravitational force on it?
An object can be considered weightless when it is in free fall or when it is in a state of apparent weightlessness, such as when it is in orbit around a planet or in a spacecraft. However, even in these situations, there is still a gravitational force acting on the object.
To understand this, we need to remember that weight is the force with which gravity pulls an object towards the center of the planet or celestial body. According to Newton's law of universal gravitation, every object with mass exerts a gravitational force on every other object with mass.
When an object is in free fall, such as during skydiving or when an astronaut is in orbit, it is essentially falling towards the surface of the Earth or another celestial body under the influence of gravity alone. Since both the object and the gravitational body are in free fall, they are effectively weightless in relation to each other. However, there is still a gravitational force acting on the object, keeping it in orbit or causing it to accelerate.
In the case of a spacecraft in orbit, it is constantly falling towards the Earth due to gravity but also moving forward fast enough that it continually misses the surface. This combination of forward motion and the gravitational pull creates a balanced state, resulting in an orbit. In this state, the object is considered weightless because it is in a continuous state of free fall.
So, to summarize, an object can be considered weightless when it is in free fall or in a state of apparent weightlessness, but there is still a gravitational force acting on it that keeps it in motion or in orbit.