PHYS 1010Q Lecture Notes - Lecture 4: Net Force, Contact Force, Free Fall
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Newton"s laws of motion, newton"s first law, newton"s second law and free fall revisited. A force is a push or a pull. The source may be gravitational, electrical, magnetic, pulling on a rope, a contact force between two objects that touch, etc. Common units of force are the newton (n) and the pound (lb) (9. 8n=2. 2 lb). Mass is a measure of the quantity of matter. It is also a measure of inertia or the sluggishness that an object exhibits in response to any effort made to start it, stop it, or change its state of motion in any way. Acceleration is a measure of the change in the state of motion of an object. Newton"s rst law is sometimes called the law of inertia. Inertia is the tendency of things to resist change in motion. Note that force has both a magnitude (amount) and a direction. Example: a rocket has a weight of 10,000n and develops 50,000n of upward thrust.