Simple Machines: More Practice
Simple Machines: More Practice
Inclined Plane
Simple Machines: More Practice
Simple Machines: More Practice
Pulley
Simple Machines: More Practice
Simple Machines: More Practice
Screw
Simple Machines: More Practice
Simple Machines: More Practice
Lever
Simple Machines: More Practice
Simple Machines: More Practice
Wheel and Axle
Simple Machines: More Practice
Simple Machines: More Practice
Wedge
Simple Machines: More Practice
Simple Machines: More Practice
Lever
Simple Machines: More Practice
Simple Machines: More Practice
Two levers!
Simple Machines: More Practice
Simple Machines: More Practice
Wedge
Simple Machines: More Practice
Simple Machines: More Practice
Inclined Plane
Simple Machines: More Practice
Simple Machines: More Practice
Pulley
Simple Machines: More Practice
Simple Machines: More Practice
Two levers again!
Mechanical Advantage and the Inclined Plane: Learning GoalThe student will be able to explain the concept of
mechanical advantage and investigate, in quantitative terms, the mechanical advantage of an inclined plane (C3.4, C2.6).
Mechanical Advantage and the Inclined Plane
SPH4C
The Inclined Plane
An inclined plane is simply a ramp that moves something horizontally as it moves vertically (and stairs may be included).
Load
A load is a mass or weight that is being supported (and possibly being moved).
Load distance
The load distance for the inclined plane is the vertical distance, or height, of the inclined plane.
Effort distance
The effort distance is the total distance the load is being moved: the length of the inclined plane.
IMA
The ideal mechanical advantage (or IMA) is defined as the ratio of the effort distance to the load distance:
height
length
d
dIMA
L
E
IMA: Example
A wheelchair ramp is 9.0 m long and has a vertical rise of 1.5 m. What is the ideal mechanical advantage of the ramp?
IMA: Example
A wheelchair ramp is 9.0 m long and has a vertical rise of 1.5 m. What is the ideal mechanical advantage of the ramp?
?:
5.1
0.9:
IMAUnknown
mheight
mlengthGiven
IMA: Example
A wheelchair ramp is 9.0 m long and has a vertical rise of 1.5 m. What is the ideal mechanical advantage of the ramp?
?:
5.1
0.9:
IMAUnknown
mheight
mlengthGiven
IMA: Example
A wheelchair ramp is 9.0 m long and has a vertical rise of 1.5 m. What is the ideal mechanical advantage of the ramp?
?:
5.1
0.9:
IMAUnknown
mheight
mlengthGiven
0.65.1
0.9:
:
m
mIMASolve
height
lengthIMASelect
Load force and effort force
This mechanical advantage should also be reflected in the reduction of the force required to move the load:
The load force is the weight of the load and the effort force is the force that is actually exerted to move the load.
AMA
The actual mechanical advantage (or AMA) is defined as the ratio of the load force to the effort force:
E
g
E
L
F
F
F
FAMA
AMA: Example
A person exerts a force of 207 N to move herself and her wheelchair (total mass 95 kg) up the ramp. What was the actual mechanical advantage of the ramp?
AMA: Example
A person exerts a force of 207 N to move herself and her wheelchair (total mass 95 kg) up the ramp. What was the actual mechanical advantage of the ramp?
?:
931)8.9)(95(
207:
2
AMAUnknown
NkgmgFF
NFGiven
sm
gL
E
AMA: Example
A person exerts a force of 207 N to move herself and her wheelchair (total mass 95 kg) up the ramp. What was the actual mechanical advantage of the ramp?
?:
931)8.9)(95(
207:
2
AMAUnknown
NkgmgFF
NFGiven
sm
gL
E
AMA: Example
A person exerts a force of 207 N to move herself and her wheelchair (total mass 95 kg) up the ramp. What was the actual mechanical advantage of the ramp?
?:
931)8.9)(95(
207:
2
AMAUnknown
NkgmgFF
NFGiven
sm
gL
E
5.4207
931:
:
N
NAMASolve
F
FAMASelect
E
L
Why is AMA lower than IMA?Actual mechanical advantage is always going to be
lower than ideal mechanical advantage.
Why is AMA lower than IMA?Actual mechanical advantage is always going to be
lower than ideal mechanical advantage. Why?
Why is AMA lower than IMA?Actual mechanical advantage is always going to be
lower than ideal mechanical advantage. Why?
Because the effort force also has to overcome friction.
Efficiency
The percent efficiency of a machine is determined by:
%100% IMA
AMAefficiency
Example
For the wheelchair ramp in our example, the efficiency would be:
Example
For the wheelchair ramp in our example, the efficiency would be:
%75%1000.6
5.4% efficiency
More Practice
Efficiency and Inclined Planes Lab Activity
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