1. Section 2-4

2. The force that opposes the downward motion of falling objects. The upward push of air on a falling object. A lighter object feels more air resistance than a heavier object so heavier object will hit the ground first. A sheet of paper fells more air resistance than a round ball because of the piece of paper has more surface area so the air pushes on the paper with more force.

3. Constant speed an object reaches as it falls, due to air resistance equaling the force of gravity. When first drop speed is equal to 0. The speed increases as it falls. At some point, the upward force of air resistance is equal to the downward pull of gravity and the speed of the object stops increasing. Vacuum – there is no air in a vacuum. A vacuum is empty space. There is no air resistance. If two different sized objects are dropped in a vacuum they will hit the ground at the same time. All objects fall at the same speed in a vacuum.