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• linear movement is a straight line
• circular motion is movement in a circle
• reciprocating motion is movement backwards and forwards along a straight line
• oscillating motion is movement backwards and forwards along an arc of a circle
• there are 3 functions of mechanism, conversion of motion, transmission of motion and control of motion
• conversion of motion is used to change one type of motion to another
• transmission of motion is used to change the place of movement
• control of motion can control speed of movement, distance of movement, direction of movement, and force produced by movement
• in the first class lever, fulcrum is between the load and the effort
• in second class lever, load is between fulcrum and effort
• there are 4 types of linkages, reverse motion linkage, four-bar linkage, bell crank linkage and crank and slider linkage
• mechanisms help to move and control things
• mechanical system is used to change one kind of movement into another
• a linkage consists of a system of rods or other rigid materials connected by joints or pivots
• 2 ways to conduct research, search online and ask and do interviews
• open looped system has no feedback so it cannot respond to changes in the environment
• closed loop system can respond to changes in the environment using feedback from within the system
• in third class lever, effort is in between load and fulcrum
• in a third class lever, effort is in between load and a fulcrum
• there are 4 types of motion, linear, rotary, oscillating, and reciprocating
• structural strengthening

  triangulation

  ribs

  braces

  rigid central core

  honeycomb

  stiffened folding

  lamination
• dynamic load is a force that changes in size, position or direction
• static load is basically something that doesnt move
• external force

  eg : wind force
• tension is the pulling of something. eg : pulling on a rubber band
• compression force is the squeezing of something

  eg: squeeze a sponge
• torsion force is the twisting of something
• shear force is the sliding of something eg: cutting paper with scissors
• bending force is the bending of something
• functions of structures

  support a load ( chair )

  protect something ( house )

  contain things ( cup of water )

  span between points ( bridge )
• there are 2 types of structures

  frame and shell
• natural frame (tree branch)

  natural shell (turtle shell)
• manmade structures

  manmade frame (shoe rack)

  manmade shell (rubbish bin)
• what makes a structure?


  resist force

  not collapse during use

  hold parts in the right place
• gears

  rack and pinion gear

  worm gear

  bevel gears

  spur gears
• gear ratio

  driven number of teeth/ driver number of teeth
• types of switches

  slide switch

  rocker switch

  toggle switch

  push button switch

  micro switch

  reed switch

  tilt switch
• SPST (torchlight)

  SPDT (fan speed control)

  DPST (control two circuits)

  DPDT (reverse switch for motion)