# Simple Machines - PowerPoint PPT Presentation

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## Simple Machines

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### Types of Simple Machines How do machines make work ... What are simple machines? A Simple Machine is a device that ... The gear ratio is found by dividing the ... – PowerPoint PPT presentation

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Title: Simple Machines

1
Simple Machines
2
Types of Simple Machines
3
How do machines make work easier?
• Machines make work easier by
• multiplying the size of the force
you exert (such as in this
pulley
system).

4
• Machines also make work easier by changing
direction of the force. Example A force on the
rope downward, hoists the weight upward.

5
What are simple machines?
• A Simple Machine is a device that does work with
one movement.

6
LEVERS
• A lever is a bar that is free to pivot, or turn
at one fixed point. The fixed point is called a
fulcrum.

7
• The part of the lever on which the effort force
is applied is called the effort arm.
• The part of the lever that exerts the resistance
force is called the resistance arm.

8
First Class Lever
Examples pliers, scissors, prybar
9
Second Class Lever
Examples wheel barrow, nut cracker,
10
Third Class Lever
11
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12
PULLEYS
• A pulley is a grooved wheel with a rope or chain
that works something like a first class lever.

13
Comparing pulleys to levers
14
Pulleys can be FIXED or MOVABLE.
• The movable pulley has a greater mechanical
advantage and therefore multiples the effort
force by a greater amount.

15
ALSO More pulleys --More rope--Less effort
16
WHEEL AND AXLE
• Simple machine consisting of two wheels of
different sizes that rotate together. The smaller
wheel is usually called the axle. (Effort force
usually applied to larger wheel.)

17
Gearsmodified wheel axle
• The effort is applied to one gear. The gear
ratio is found by dividing the radius of the
effort gear by the radius of the resistance gear.
(This is the ideal mechanical advantage for the
gears.)

18
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19
The SCREW
• A screw is an inclined plane wrapped in a spiral
around a cylindrical post.

20
The wedge
• A wedge is an inclined plane with one or two
sloping sides.
• (knife and axe blades are wedges)