PHY 205 Lecture Notes - Lecture 8: Parachuting, Vacuum Tube, Net Force
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In a vacuum tube, a feather is seen to fall as fast as a coin. This is because air resistance doesn"t act in a vacuum. Speed and acceleration are actually entirely different concepts. An object will accelerate when it is pushed or pulled with a net force. Friction is a force like any other force and affects motion. Friction occurs in all of these (solids sliding over one another, fluids, air) When you stand on one foot instead of two, the pressure you exert on the ground is twice. The reason a 20kg rock falls no faster than a 10kg rock in free fall is that the force/mass ratio is the same. Kevin is heavier than suzanne, but both use the same size parachute. Kevin has greater terminal speed compared with suzanne because he has to fall faster for air resistance to match his weight. A force interaction requires at least a(n) pair of forces.