Module -6
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Module Objectives
Identify inclined planes, wedges and
screws.
 Describe the purpose and application of
each one of them.
 Calculate the mechanical advantage of
inclined planes, wedges and screws.
 Conduct practical tasks to demonstrate
the function of inclined planes, wedges
and screws.

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What is an inclined plane? How do
they make our work easier?
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Inclined Plane
An inclined plane is a simple machine. It has a slanted (sloped)
surface used to move objects to another height with less force
The advantage of using an
inclined plane has been
known for thousands of
years -Pyramids.
 Using an inclined plane to
raise an object to a given
height, the object must be
moved a longer distance,
but with less effort needed.

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Inclined Planes
A lot of effort is needed to
raise a given load a short
distance straight
upwards, whereas much
less force is needed to
raise it gradually at an
angle over the longer
distance of an inclined
plane.
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Inclined Plane

Give Real Life examples on Inclined
Planes?
 Stairs
 Ramp
 Ladder

Class Activity Page -5
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Mechanical Advantage
of Inclined Plane
MA = D / H
Mechanical Advantage
(MA) = 3m/1m = 3
Calculating the effort needed to raise a known load can
be done using this formula:
Effort = Load/MA
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Problems:

Calculate the Mechanical
advantage and the effort
needed for the following
inclined plane?

Calculate the Mechanical
advantage and the effort
needed for the following
inclined plane?
2m
2 m height
600 N
600 N
MA=D/H= 4/2= 2
Effort= Load/MA= 600/2= 300 N
MA= D/H= 6/2=3
Effort= Load/MA= 600/3= 200 N
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Page 12-13
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What is a wedge? Why do we need a
wedge and where?
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Wedge
A wedge is a simple machine shaped like an inclined plane.
Unlike an inclined plane a wedge can move.




Wedges are tools used to
push two objects apart.
A wedge can have a single or
two sloping surfaces.
The effort you need depends
on the relationship between
the length and width of the
wedge and the sloping
surface.
A simple device called a
wedge and feather can split
huge granite blocks.
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Wedges
Example from
real life on
wedges !!
Any more
examples??
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Wedges

Class Activity : Inclined or wedge?
Task1
Cut the tree
Wedge
Task 2
Split the wood
Wedge
Task 4
Transport logs of wood from
Inclined Plane
the truck to the shop floor
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Mechanical Advantage
of a Wedge
The sharper the angle of the wedge, the more mechanical
advantage it will have.
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Problems:
Calculate the Mechanical
advantage for the
following wedge?

Calculate the Mechanical
Advantage for the
following Wedge?
5m
5m

MA=Slope/thickness
= 35/5= 7
MA= Slope/Thickness
= 50/5 = 10
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Page 14-15
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What is a Screw? Why do we need a
Screw and where?
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Screw

A screw is a simple
machine and it is a
modification of an inclined
plane.

The threads of a screw are
like an inclined plane
wrapped around a
cylinder.
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Where do we use screws?

Give Examples on Screws?
 Different Screw Types
 Lamp
 Drill
 Cork Screw

screw-pump design to move water for
irrigation by Archimedes.
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Pitch = screw length/ number of threads
Screws
Pitch of the screw is
number of threads per
cm.
The finer the pitch of
the screw, the more
turns are required,
but the less effort is
needed to drive the
screw in.
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Mechanical Advantage
of a Screw
This means if you can twist your screw driver with
a force of 1N you can generate a force of 4N.
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Problems:

Calculate the Mechanical
advantage for the
following Screw if it is 10
cm long and has 100
threads?given that the
diameter is 1 cm
pitch=10/100= 1/10
MA= 2*pi*0.5/0.1
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