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Newton’s Laws of Motion

Newton’s Laws of Motion. Forces and Equilibrium Chapter 4 Part 1. Galileo’s Inertia. After watching Jupiter’s Moons Galileo became convinced that objects had a tendency to keep whatever state of motion they had. He called this the objects’ inertia

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Newton’s Laws of Motion

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  1. Newton’s Laws of Motion Forces and Equilibrium Chapter 4 Part 1

  2. Galileo’s Inertia After watching Jupiter’s Moons Galileo became convinced that objects had a tendency to keep whatever state of motion they had. He called this the objects’ inertia He confirmed it by doing experiments using balls rolling up and down ramps.

  3. Isaac Newton (1642-1727) Inspired by Galileo and Kepler, before he was 23 Isaac Newton laid the foundation of modern physics. Galileo inspired him to create His three laws of motion Kepler inspired his Universal Law of Gravity Newton would go on to: make discoveries in Optics and to lead efforts to find an astronomical solution to the problem of longitude by using Jupiter’s moons The first Physics, was Astrophysics.

  4. Forces, Internal and External A Force is a Push or Pull exerted on an object in a given direction. Force is measured in: (MKS) Newtons, “N” (CGS) Dyne, “d” (FPS) Pounds, “lb” Force is always a vector. Internal forces act between objects that are all in a system External Forces act between a system and thangs outside the system

  5. Types of Forces: Normal Force: A force (push) exerted by a surface. It is always directed perpendicular to the surface. Tension : A force (pull) exerted by a string, rope, chain etc. It is always exerted along the string etc. in both ways. Friction: Is a force that opposes motion, when two surfaces rub past each other, or as an object moves through a fluid Weight: The force of gravity from the local celestial body on an object, It is always toward the center of the body

  6. Free Body Diagram A free Body diagram is an abstract drawing of the forces acting between an object or objects and the environment It is as simple as possible with all vectors drawn from the point on which they act…as pulls

  7. Two Kinds of Forces Contact Forces: Act by touching the object • Normal force • Tension • Friction Field Forces: Act at a distance on an object with certain properties in a certain space (the Field) • Gravity • Electric • Magnetic

  8. Net Force Net Force: The vector sum of the forces on an object. To find it: • Break down all vectors into X & Y Components • Add like components • Use Pythagorean Thm to find Magnitude • Use inverse tangent to find direction

  9. The First Law Isaac Newton developed the idea of inertia into his First Law of Motion “An object in motion stays in motion in a straight line, one at rest stays at rest, unless a force acts on it.” Or “The velocity of an object does not change unless a net external force acts on it”

  10. Equilibrium Equilibrium is when the net force on an object is Zero. Newton’s First Law of Motion tells us that: An object is in equilibrium if and only if it has a constant velocity. The Equilibrant The Equilibrant is the force needed to balance the other forces on an object and thus achieve equilibrium It is equal to the net force but in the opposite direction

  11. Surface Friction and the coefficient of Friction Surface Friction is a force opposing the motion as surfaces slide across each other. The amount of friction is directly related to: • The Normal Force between the surfaces • How “rough” the surface on a microscopic scale, given as the “coefficient of friction” or “μ” (mu) (copy formula)

  12. Static and Kinetic Friction Static Friction opposes a force that is trying to make a stationary object move. Kinetic Friction opposes motion that is happening. Static friction between two surfaces is always greater than Kinetic friction between the same surfaces. Thus every pair of surfaces has two μ, μS & μK And μS > μK

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