So, when more than one force acts on an object, what happens?

• Two forces acting on an object in the same direction combine into one stronger force. If two people push a large rock in the same direction, they can push it with more force together than alone.
• Two forces acting on an object from opposite directions counteract each other. If two people push a large rock from opposite sides, it will move in the direction of the stronger push.
• When forces are equal and opposite to one another, they are balanced and there is no effect on the motion of the object. If two people push a large rock with equal force from opposite sides, it will not move at all.

Now read Counteracting Forces  (PDF) about how the forces of gravity and air resistance counteract each other.

How does air resistance affect how fast a feather falls? Write your answer in two to three sentences.