SIMPLE MACHINES!

1
SIMPLE MACHINES!
Technology Education Ms. Bowling
2
Simple Machines??

• Simple Machines A simple device that provides a
  mechanical advantage, such as a wheel axle,
  lever, pulley, or inclined plane.
• Compound Machines A system of two or more simple
  machines (the game mouse trap is a great
  example).

3
THERE ARE SIX SIMPLE MACHINES

• LEVER AND FULCRUM
• PULLEY
• WHEEL AND AXLE
• INCLINED PLANE
• WEDGE (Modification of Inclined plane)
• SCREWS (Modification of Inclined plane)

4
Machines do work for us.What is Work?

• In order for work to be done, two conditions must
  be
• met
• a force must move an object some distance
• and the force and distance the object moves must
  also be in the same direction.
• Therefore, if the object does not move, no work
  is being
• done.

5
Formula for Work

• In order to calculate work you need to have the
  measurement for Force and Distance.
• Force is measured in lbs (Conventional Method)
• Distance in measured in feet. (Conventional
  Method)
• WF x D

6
How do machines help us do work?

• Mechanical advantage (MA) is the factor by which
  a mechanism multiplies the force put into it,
  making work easier.
• Machines provide us with MA in the following
• ways
• A machine can increase the force
• A machine can change the direction
• A machine can increase the speed

7
LEVER AND FULCRUM

• A simple machine consisting of a rigid bar and a
  fulcrum (pivot point).
• There are three classes
• 1st class
• 2nd class
• 3rd class

8
Three classes of Levers

• The class of lever is determined by what is
  located in the middle.
• Use this diagram to help you remember.
• If the fulcrum (pivot point) is in the middle
  then the lever is a first class.
• If the resistance (load) is in the middle then
  the lever is a second class.
• If the effort (force you put in) is in the middle
  then the lever is a third class.

9
FIRST CLASS LEVER
1st class-the fulcrum is between the effort and
the Load. The closer the load is to the
fulcrum, the less effort needed to lift the load.
10
SECOND CLASS LEVER
2nd class- the LOAD is between the effort and the
fulcrum.
11
THIRD CLASS LEVER
3rd class- the EFFORT is between the Load and the
Fulcrum

• These levers are used least often because their
  MA is less than 1.
• This means the force needed to use them is
  greater than the force they can move.

12
How to calculate MA for levers

• Can be calculated in two ways
• MA Effort Arm (Distance from Fulcrum)
• Resistance arm(Distance from Fulcrum)
• MA Load/Resistance
• Effort

13
PULLEY

• Pulley A simple machine consisting essentially
  of a wheel with a grooved rim in which a pulled
  rope or chain can run to change the direction of
  the pull and thereby lift a load.

14
Pulley Systems

• There are three types of pulley systems
• 1. A FIXED PULLEY
• 2. A MOVABLE PULLEY and
• 3. A COMBINATION PULLEY
• To calculate MA, you count the of wheels
• or ropes, excluding the effort rope.

15
FIXED PULLEY

• A fixed pulley is fixed to something such as a
  ceiling, it cannot move.
• Work changes the direction of the force
• MA A fixed pulley provides a mechanical
  advantage of 1.

16
MOVABLE PULLEYS

• A movable pulley is movable either vertically
  or horizontally.
• Work changes the direction of the force
• MA A movable pulley provides a mechanical
  advantage of 1.

17
COMBINATION PULLEY

• A combined pulley is a combination of the fixed
  and movable, sometimes called a block and
  tackle.
• Work changes the direction of the force
• MA A combination pulley provides a larger
  advantage. This example has a mechanical
  advantage of 2.

18
WHEEL AND AXLE

• Wheel and Axle a simple machine consisting of
  two concentric wheels.
• Work Increases the speed and changes direction
• MA wheel diameter/axle diameter (5/1 5)

19
INCLINED PLANE

• Inclined plane A simple machine used to raise
  or lower a load by rolling or sliding it.
• Work Increases the force
• MA Slope / height
• Here it is 4.

20
Inclined planes

• One of the most common examples of an inclined
  plane is a staircase, which allows people to move
  with less effort than climbing straight up a
  ladder requires.
• The drawback is that more distanced is traveled.

21
WEDGES

• A piece of material, such as metal or wood, thick
  at one edge and tapered to a thin edge at the
  other
• Used for splitting, tightening, securing, or
  levering.
• The wedge is an inclined plane.

22
SCREWS

• The screw is an incline plane that is wrapped
  around a central axis.
• The distance moved by the resistance is going to
  be the pitch (the distance advanced in a single
  turn) of the thread times the number of turns of
  the screw.