Which of these IS an example of balanced forces?

A. a book on a shelf
B. air rushing out of a balloon
C. rolling over and falling off the bed
D. a car speeding up at a constant rate

The summit of chimborazo, in ecuador, which is at a distance of about 6,384 km from the earth's center. the bottom of the mariana trench, in the western pacific ocean, which is nearly 6,370 km from the center of the earth. on the surface of earth on the equator line.

What is relative velocity? in which condition is relative velocity known by adding the velocity of the first body and that of the second body

When the displacement of a mass on a spring is 12a the half of the amplitude, what fraction of the mechanical energy is kinetic energy? at what displacement, as a fraction of a, is the mechanical energy half kinetic and half potential?