Simple Machines Part 1

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Simple Machines Part 1
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6 Simple Machines

• Lever
• Wheel Axle
• Pulley
• Inclined Plane
• Wedge
• Screw

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Simple Machines are used to

• Transfer Kinetic Energy (energy of motion)
• Reduce effort needed to move a load
• Change the direction or amount of motion
• Change the type of motion(rotary to straight)

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Key Term

• Effort (E) Input force which is applied by the
  user.
• Load (R) Output forced. Also the force
  resisting effort.

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Key Term

• Mechanical Advantage (MA) is a measure of how
  much the effort is decreased by the simple
  machine.
• Mechanical Advantage Load / Effort
• Actual Mechanical Advantage
• MA R/E

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Key Term

• Work The force applied on an object times the
  distance traveled by the object.
• Work Force Distance D d

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Levers Examples
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Levers
E
R
Fulcrum

• To be balance or in equilibrium the effect of
  each force must be equal.

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Key Term

• Moment Force Distance to fulcrum

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Levers in Equilibrium
300 lbs.
1200 lbs.
4ft.
1ft.
Fulcrum

• Moment 1 Moment 2
• Force 1 Distance 1 Force 2 Distance 2
• 300 lbs. 4ft. 1200 lbs. 1ft.
• 1200 ft. lbs. 1200 ft. lbs.

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Lever Mechanical Advantage
1200 lbs.
300 lbs.
4ft.
1ft.

• Mechanical Advantage Load/Effort
  1200lbs/300lbs 4
• MA Length of Effort/Length of Load LE/LR
  4ft./1ft. 4
• MA has no units.

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Lever General Terms
R
E
LE
LR

• E Effort
• R Load
• LE Length from fulcrum to Effort
• LR Length from fulcrum to Load (R)

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MA for levers

• MA Length of effort/Length of Load LE/LR
• MA R / E
• LE/LR R / E
• LE E LR R

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Lever Problem 1

• Suppose you given a 6 board and a log to use as
  a fulcrum and you wanted to lift a large object a
  short distance. Where would you place the log?
  Why?

Locate the log as close as possible to the load.
MA will increase
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Classes of levers 1st Class

• The fulcrum located in the center of the lever
  arm, and the effort and load at opposite ends.

R
E
If LE gt LR then MA gt 1 If LE lt LR then MA lt 1
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Classes of levers 2nd Class
E
R

• Since LE gt LR, then MA gt1

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Classes of levers 3rd Class
E
R

• If LE lt LR then MA lt 1

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Lever Problem 2
R
E
LE
LR

• Given LR 2ft., LE 6ft., E 1lbs, find R
• LEE LRR so 61 2R then R 3 lbs.

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Lever Problem 3
R
E
LE
LR

• Given R8lbs, LE4ft, E4lbs, find LR
• LEE LRR so 44 LR8 then LR 2ft.