Simple Machines: More Practice. Inclined Plane Simple Machines: More Practice.

Simple Machines: More Practice


Inclined Plane


Pulley


Screw


Lever


Wheel and Axle


Wedge


Lever


Two levers!


Wedge


Inclined Plane


Pulley


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


?:

5.1

0.9:

IMAUnknown

mheight

mlengthGiven

IMA: Example


?:

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


?:

931)8.9)(95(

207:

2

AMAUnknown

NkgmgFF

NFGiven

sm

gL

E

AMA: Example


?:

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.


lower than ideal mechanical advantage. Why?


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

Simple Machines: More Practice. Inclined Plane Simple Machines: More Practice.

Documents

Transcript of Simple Machines: More Practice. Inclined Plane Simple Machines: More Practice.