science - about volcanic eruptions and earthquake

• Earthquake


  Sudden movement or vibration of the Earth's rocky outer layer
• Volcanic earthquake


  Earthquake caused by the movement of magma beneath the surface of the Earth
• Cause of volcanic earthquakes

  1. Pressure within the magma chamber is greater than the strength of the crust

  2. Gases inside the magma chamber are mixed with magma, causing bubbles to rise and push against the Earth's crust

  3. Magma chamber is overloaded, causing eruption
• Scientists cannot predict earthquakes, but can point out where fault lines are to know where earthquakes are likely to occur
• The largest earthquake ever recorded was in Chile in 1960, measuring 9.6 on the Richter scale
• The largest earthquake in the US was a 9.2 magnitude in Alaska in 1964
• Earthquakes


  Can cause huge waves in the ocean called tsunamis
• Movement of tectonic plates

  Forms large mountain ranges like the Himalayas and the Andes
• Earthquakes can happen in any kind of weather
• Simple machines


  Require human energy in order to work, make work easier by implying less force to do the same amount of work
• Simple machines

  • Scissors
  • Coffee grinder
• Compound/complex machines


  Consist of two or more simple machines
• Compound/complex machines

  • Bicycle
  • Sewing machine
• Compound/complex machines


  • Use a variety of simple machines like levers and screws
• Lever


  A straight rigid object like a board or bar which revolves on a turning point called a fulcrum, makes work easier by using leverage which multiplies the force
• Parts of a lever

  • Load/resistance
  • Effort/force
  • Fulcrum
  • Resistance arm
  • Effort arm
• Classes of levers

  • First class: Fulcrum between load and effort
  • Second class: Fulcrum at one end, load in middle, effort at other end
  • Third class: Fulcrum at one end, load at other end, effort in middle
• First class lever


  • Scissors
  • Seesaw
• Second class lever

  • Wheelbarrow
  • Paper cutter
• Third class lever


  • Tweezers
  • Human forearm
• Inclined plane


  A simple machine with a sloping surface that lessens the effort exerted in transporting weight over a distance and height
• Inclined planes have been used since prehistoric times to move heavy objects
• Wedge


  A simple machine consisting of two inclined planes, used to cut, split, tighten, hold back, and scrape objects
• Wedges

  • Axe
  • Needle
  • Knife
  • Chisel
  • Staple
• Wedges are used to separate objects apart, like cutting or splitting
• Wedges used for cutting

  • Kitchen knife
  • Axe
• Wedge


  A simple machine that consists of two inclined planes giving it a thin end and a thick end
• Wedge


  • Used to separate an object apart
  • Used to cut, tear, or break something into two
• Examples of wedges used for separating things


  • Chisel
  • Axe
• Examples of wedges used for holding things together

  • Nails
  • Push pins
  • Staples
  • Thumbtacks
• Screw


  A twisted inclined plane that allows movement from a lower position to a higher position but at the same time moves in a circle
• Wheel and axle


  The wheel itself is not a machine, it becomes a machine when it combines with an axle
• Examples of wheel and axle

  • Electric fan
  • Bike
  • Revolving door
  • Merry-go-round
• Pulley


  A wheel that carries a flexible rope, cord, or belt on its rim, made of a wheel and a rope
• Examples of pulley uses

  • Window blinds and drapery
  • Raising and lowering sails on ships
  • Raising and lowering heavy cargo
  • Elevators
• Types of pulleys


  • Fixed pulley
  • Movable pulley
  • Block and tackle
• Simple machines are simple tools that multiply the amount of work to make work easier
• Types of simple machines


  • Lever
  • Inclined plane
  • Wedge
  • Screw
  • Wheel and axle
  • Pulley
• Our galaxy is called the Milky Way
• The bright light is our solar system