Simple machine is a term used to describe certain parts and pieces A simple machine is an apparatus that is made of a small number of pieces and permits us to use more efficiently or more comfortably mechanical energy It helps us reduce the necessary force to perform a task ID: 629318
Download Presentation The PPT/PDF document "Key POINTS Sowing machines, washer machi..." is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1Slide2Slide3Slide4Slide5Slide6
Key
POINTS
Sowing machines, washer machine, coffee machine, etc. all involve the use of a machine to perform a variety of operations in domestic or industrial situations. The machines themselves are made of many parts and pieces.
Simple machine is a term used to describe certain parts and pieces.
A simple machine is an apparatus that is made of a small number of pieces and permits us to use more efficiently or more comfortably mechanical energy. It helps us reduce the necessary force to perform a task.
Simple machinesSlide7
Key
POINTS
These machines may help us change the direction or the nature of an action, for instance, movement.
We will see in this section six types of simple machines that are frequently used:
Inclined plane
Wedge
Wheel
and axle
Levers
Pulley
Simple machinesSlide8Slide9Slide10Slide11Slide12
Key
POINTS
Levers
: a lever is solid bar that rotates, or turns around a fixed point. The bar can be straight or curved. The fixed point is called the fulcrum. A lever can multiply the strength of a force applied to an object. If you apply a force downward on one end of a lever, the other end can lift a load. There are three types of levers:
Simple machines
a) First-class lever
: A fulcrum is located between an input force and an output force. An example for this is a crow bar.
INPUT FORCE
OUTPUT FORCE
FULCRUMSlide13
Key
POINTS
Simple machines
b) Second-class lever
: The output force is located between the input force and the fulcrum. We use this type of lever if we need a greater output force. An example of this type of lever is a bottle-top opener.
INPUT FORCE
OUTPUT FORCESlide14
Key
POINTS
Simple machines
c) Third-class lever
: The input force is located between the output force and the fulcrum. Use this type of lever to reduce the distance over which you apply the input force or increase the speed of the end of the lever.
INPUT FORCE
OUTPUT FORCESlide15
CATAPULTS: LEVERSSlide16Slide17Slide18Slide19
Some
MATH
Lever mathematics
There is a mathematical relation that can be used to calculate the amount of force needed to lift an object:
F
1
x
d
1
=
F
2
x
d
2
Where
F
is
force
measured in
Newtons
(
N
) and
d
is
distance
measured in
meters
(
m
)
A force needed to lift an object is equal to the
weight
of that object in Newtons.
F
1
F
2
d
1
d
2Slide20
F
1
F
2
FORCE OF RESISTANCE
MOTOR FORCESlide21
F
1
FIRST SITUATION
SECOND SITUATION
F
2
F
1
F
2
A rock weighing
100 N
(F
1
) is placed on the left side at
one meter
from the fulcrum. Calculate the
Motor force
(F
2
) knowing that there is a distance of
two meters
between the fulcrum and the
motor force
That same rock is now placed at
two meters
away from the fulcrum. Calculate the
force of resistance
(
F
1
)
knowing that there is a distance of
two meters
between the fulcrum and the force of resistance.
F
1
x
d
1
=
F
2
x
d
2
100 N x 1 m = F
2
x 2 m
F
2
= 50 N
F
1
x
d
1
=
F
2
x
d
2
100 N x 2 m = F
2
x 1 m
F
2
= 200 NSlide22
What is the distance between the fulcrum and the input force (75 N) knowing that the output force is 50 N and the distance is 7 meters
?
What input force is needed to lift a 60 N object, knowing that the distance from the fulcrum for the object is 2.5 meters and your distance from the fulcrum is 6 meters?
Calculate the weight of your younger sister sitting on a see-saw knowing that you need 30 N to lift her. Your position is 3 meter from the fulcrum and she is sitting at 6 m away from the fulcrum. In addition, calculate the amount of your work on your behalf.Slide23Slide24Slide25Slide26Slide27
FIXED PULLEY
MOVABLE PULLEYSlide28Slide29Slide30Slide31
Key
POINTS
Inclined
plane or ramp
: a ramp is an inclined surface placed at an angle with the horizontal surface. It helps us in reducing the force needed to lift an object upward or to lower this object.
Simple machinesSlide32
In the first situation, the force exerted to lift the heavy box is equal to the mass of that box.
In the second and third situation, by using a ramp, you exert less force in lifting and displacing the box, but you need more distance to perform this task. It is also important to note that having a smaller angle between the ramp and the ground helps us in using less force to perform the task.Slide33Slide34
Key
POINTS
Wedge
: a wedge is a simple machine that has a thick end and a thin end. They are used to cut, split or pierce objects and to hold objects together. Inclined planes are stationary (Don’t move) whereas wedges can move to do work.
Simple machinesSlide35Slide36
Key
POINTS
Wheel
and axle
: a wheel and axle is a simple machine made of a wheel attached to a shaft, or axle. They act like a rotating collection of levers. The axle at the wheel’s center is like a fulcrum. Some examples are bicycle and car wheels, screwdrivers, steering wheels, doorknobs and electric fans.
Simple machinesSlide37Slide38Slide39Slide40Slide41