Question

We refer to astronauts in space as weightless, but not without mass. Why?

Short answer

The astronauts are referred to as weightless, but they are not massless due to the inefficiency of gravity.

Step-by-step solution

Defining the weight and mass

The force exerted on the body due to gravity is referred to as weight. Its unit is Newton (N). It is a vector quantity with direction and magnitude. Weight is dependent on mass.

Mass is a measure of the quantity of matter within the body. Its unit is the kilogram (kg). It is a scalar quantity with only magnitude. Mass does not depend on weight.

Describing whether the astronauts are weightless or massless

In space, gravity is considered zero. The astronaut feels weightlessness. The force due to gravity is zero, while an astronaut is not massless because the mass is independent of weight or gravity.

Space is a vacuum, so we know that vacuum does not exhibit gravity. In addition, the astronauts are away from the earth's surface or atmosphere. Hence, they feel less gravitational force.