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Energy!

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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Energy!

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  1. Energy! Notes – 30Oct2014 Pappalardo – Science Gr8

  2. 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

  3. Roller Coasters (fun)

  4. Roller Coasters (copy diagram)

  5. GPE(copy diagram)

  6. Pendulums(copy diagram)

  7. Springs & Rubber Bands(copy diagram)

  8. 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!

  9. 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 

  10. 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)

  11. 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)

  12. 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

  13. 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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