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Energy!. Notes – 30Oct2014 Pappalardo – Science Gr8. PE  KE  PE, etc. (copy). Potential Energy (PE) = stored energy an object/material has due to its position, condition, or chemical composition

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Notes – 30Oct2014

Pappalardo – Science Gr8

Pe ke pe etc copy

PE  KE  PE, etc. (copy)

  • Potential Energy (PE) = stored energy an object/material has due to its position, condition, or chemical composition

    • Think: stretched rubber band (elastic PE), height above ground (gravitational PE), or the energy stored in chemical bonds (chemical PE – like in food!)

  • Kinetic Energy (KE) = the energy of moving objects

    • Depends on MASS and SPEED/VELOCITY

    • Like momentum, it can be transferred between objects

    • Think: Newton’s Cradle, bowling, car crashes

Roller coasters fun

Roller Coasters (fun)

Roller coasters copy diagram

Roller Coasters (copy diagram)

Gpe copy diagram

GPE(copy diagram)

Pendulums copy diagram

Pendulums(copy diagram)

Springs rubber bands copy diagram

Springs & Rubber Bands(copy diagram)

Newton s laws again copy

Newton’s Laws (again) (copy)

  • Newton’s 1st Law of Motion: the law of inertia

    • Objects at rest tend to stay at rest…

    • Objects in motion tend to stay in motion (in a straight line, at a constant speed)…

    • UNLESS outside forces act on the object (a push, a pull, gravity, friction, air resistance, etc.)

  • Newton’s 2nd Law of Motion: F = ma

    • Force (Newtons) = Mass (kg) x Acceleration (m/s2)

    • The more massive something is, the more force it will take to accelerate it in any direction!

    • Think: it takes more force to stop or start a real car than it does to play with a toy car!

Newton s laws again copy1

Newton’s Laws (again) (copy)

  • Newton’s 3rd Law of Motion: Action & Reaction

    • For every action, there is an equal – but opposite – reaction

    • Think: pushing off a skateboard, hitting a ball with a baseball bat, Teddy & Matthew or Nat & Lowen on scooters 

Work copy

Work (copy)

  • Work is done only when a force is exerted over a distance

    • Think: lifting books up, pushing a cart, pulling on a wagon

    • Work (Joules) = Force (Newtons) x Distance (meters)

  • Power is the amount of work done in a period of time

    • Think: lifting weights quickly instead of slowly

    • Power (Watts) = Work (Joules) ÷ Time (Seconds)

Simple machines copy

Simple Machines (copy)

  • Inclined Plane = a slope that does not move (ramp)

  • Wedge = two sloping sides that meet at a point (axe blade)

  • Screw = inclined plane wrapped around a cylinder (screw)

  • Wheel & Axle = a wheel on a shaft, or axle (steering wheel)

  • Pulley = a rope that fits into a grooved wheel (used to raise and lower flags, for example)

Simple machines copy1

Simple Machines (copy)

  • Lever = rigid bar that turns around a fixed [fulcrum] point

    • 1st Class:

      • Fulcrum in the middle between the input & output forces

      • Think: seesaws, pliers, oars, soda can tabs

    • 2nd Class:

      • Output force is between the input force and fulcrum

      • Think: wheelbarrows, nutcrackers, bottle openers

    • 3rd Class:

      • Input force is between the fulcrum and output force

      • Think: shovels, brooms, fishing rods, baseball bats, toothbrushes, tweezers, golf clubs, rakes, human forearms

Compound machines copy

Compound Machines (copy)

  • Compound Machines = two or more simple machines working together

  • Think: Gears (wheel & axle with teeth)

  • Think:

    • pencil sharpeners (gears, levers, wedges)

    • Scissors (wedges, levers)

    • Axes (wedges, levers)

    • Roller coasters, Ferris wheels, bicycles

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