# Newton’s Second Law of Motion

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Newton’s Second Law of Motion
Chapter 6

Newton’s Second Law of Motion
The net force acting on an object causes that object to accelerate in the direction of the net force. Greater the force = Greater acceleration. F F

Newton’s Second Law of Motion
Inverse relationship between mass and acceleration!!! The greater the mass, the more force it takes to accelerate an object at the same rate of a less massive object!!! F F

Newton’s Second Law of Motion
The relationship between force, mass, and acceleration is expressed as: F = ma SI unit = kg x m/s² = N

Sample Problem What is the force of a baseball weighing 0.06 kg that is accelerating towards a wall at 5,500 m/s²? m = 0.06 kg a =5,500 m/s² F = ma = (0.06 kg x 5,500 m/s²) = 330 N

Newton’s Third Law of Motion
Single isolated forces cannot exist! Forces always exist in pairs (action- reaction pair). “Whenever two objects interact, the force exerted on one object is equal in strength and opposite in direction to the force exerted on the other object.”

Force of the astronaut on the satellite
Force of the satellite on the astronaut The most important thing to keep in mind about action-reaction pairs is that each force acts on a different object.

How does a nail get driven into a piece of wood by a hammer?
Example 2: How does a nail get driven into a piece of wood by a hammer? Force of the nail on the hammer Force of the hammer on the nail Force of wood on nail

Assignment Pg. 138 #1, 2, 3 & 5 Pg. 140 # 1, 2, & 4