One 7.0 kg ball is lifted to a storage shelf 1.0 m above the floor. A second 7.0 kg ball is lifted to a storage shelf 2.0 m above the floor. Which of the following best explains why the measured force of gravity on eah ball is nearly identical?
a. The final potential energy of each ball increased.
b. The amount of work required to lift each ball is identical.
c. The distance of each ball from the Earth's center of mass is almost identical.
d. The gravitational force of each ball on the other cancels out the force of Earth's gravity.
