According to ptolemy's model of the movement of celestial bodies,
a. the earth rotates around the sun.
b. the sun is the center of the universe.
c. the earth rotates around the moon.
d. planets orbit in circular paths around the earth.

1. explain how you calculate the net force in any direction on the box. 2. suppose an upward force of 15n is added to the box. what will be the net vertical force on the box? 3. what force could be applied to the box to make the net force in the horizontal direction zero? explain. 4. suppose a force of 25n to the right is added to the box. what will be the net force to the right?