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# Energy! - PowerPoint PPT Presentation

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

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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

• 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 (copy diagram)

GPE(copy diagram)

Pendulums(copy diagram)

Springs & Rubber Bands(copy diagram)

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