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 (fun)

Roller Coasters (copy diagram)

GPE (copy diagram)

Pendulums (copy diagram)

Springs & Rubber Bands (copy diagram)

Newton’s Laws (again) (copy) Newton’s 1 st 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 2 nd Law of Motion: F = ma Force ( Newtons ) = Mass ( kg ) x Acceleration ( m/s 2 ) 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 3 rd 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 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 1 st Class: Fulcrum in the middle between the input & output forces Think: seesaws, pliers, oars, soda can tabs 2 nd Class: Output force is between the input force and fulcrum Think: wheelbarrows, nutcrackers, bottle openers 3 rd 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