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## PowerPoint Slideshow about ' Energy!' - jordan-kirby

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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

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) (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 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)

- 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 (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 = 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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