We will study the force of gravity in more details at the end of the course.
For the moment we will use
with
Another more intricate but very important example is below. This is also in your textbook, Fig 6.10 and surrounding text.
Note that you feel heavier or lighter when an elevator starts or stops. This is your weight. If the cable was to suddenly break, you and the elevator would be in free fall and the scale would read zero. You would be weightless.