Final answer:
When no forces are exerted on an object, it is in a state where the net force is zero, resulting in no acceleration and maintaining a constant velocity due to inertia. Such a state can lead to weightlessness in the absence of gravity, as in the case of an astronaut in deep space.
Step-by-step explanation:
When something has no forces exerted on it, it means that the net force acting on the object is zero. An example of this could be a bowling ball that has been thrown and is now moving along a bowling alley; after the hand is no longer in contact with the ball, no additional forces are being exerted on it (assuming no air resistance or friction). The ball will continue to move at a constant velocity because of inertia, which is the tendency of an object to resist changes in its state of motion unless acted upon by a force.
According to Newton's second law, when the net force is zero, the acceleration of the object is also zero; therefore, if an object was at rest, it stays at rest, or if an object was in motion, it continues to move at a constant velocity. This concept is related to the conservation of mechanical energy, where in the absence of non-conservative forces (like friction or air resistance), the mechanical energy of an object remains constant.
In a situation where an astronaut is in space far from any significant gravitational forces, she can be described as weightless because there are no forces acting upon her, including gravity. However, her mass remains unchanged at 70 kg. This illustrates that the sensation of weight is due to the force of gravity and not the presence of mass itself.