Why is the invention of the wheel so important
Why Invention of the wheel is important
welcome to the video tutorials of
mechanisms by mechanism Euler
without a doubt the invention of the
will is one of the most important
inventions in human history why was it
so important when you do a google search
on the topic you will find many
explanations which explain the benefits
of the will but they do not mention the
core reason of the importance of the
wheel with this video I will try to
include my two cents on the subject
first let's ask ourselves what the power
requirement to move a load from point A
to B on a flat surfaces you can assume
any valid value for the load or any
other input you need to calculate this
power it is paradoxical that the power
we consume to carry the load is zero
that does not make sense
it is 0 because the
of the power in the engineering field is
vector product of force and velocity as
you can see in the slide shown the force
vector and velocity vector have 90
degree angle between them
this makes the result of this vector
product zero you may say okay I got it
but then why do I get tired when I carry
a heavy load the answer is you will get
tired even if you don't walk a heavy
load will put a lot of pressure on your
skeleton and your muscles
the solution to this problem is to carry
the load indirectly we all dragged heavy
loads rather than to carry them this
behavior allows us to put the weight on
the ground and we overcome the friction
force while we're dragging this friction
force is comparably smaller than the
weight of the actual load to reduce the
friction force even more we have to
create some mechanism to drag the load
one solution used by many American
Indians is the Travoy shown in this
photo now
let's investigate the problems of using
a travois in this design the friction
between the load and the ground is
reduced by having X shaped poles on the
horseback this reduces the friction
substantially but it does put some load
on the horse's shoulders
let's do a leverage calculation of this
mechanism a hundred kilogram load put in
the middle of the pole
where the midpoint is the point between
the poles attached on the horseback and
touch the ground assuming that the pole
length from shoulder to ground is three
meters this arrangement will put a 50
kilogram load on the shoulders of the
horse for a 300 kilogram load it will
jump to 150 for the horse apparently
this is not a very good arrangement for
the horse
also the pole ends that are touching the
ground are subject to heavy wear and
tear
ordinary wheelbarrows are similar in
operation to the Travoy with a slight
improvement the addition of the will at
the end reduces the friction to a
minimum this is due to the fact that the
rolling resistance is much smaller than
dragging friction
however the operator is burdened with
carry a fraction of the load we can do
much better than that
a much better solution comes from China
where fulcrum load weight and reaction
force all lined up on a vertical line
passing through the will touching the
ground
this arrangement removes any load on the
person pushing it and enable him to
carry much heavier loads
they even went further to use sales to
help push whenever the wind was coming
from the desired direction
the same idea has been used by Americans
to carry large logs with ease by using
big wheels where the load was hanging
from the axle of the wheels
here is another view of the big wheel
in short to carry loads by will or
slides the load should be on the axle
for two-wheeled carriages or between
axles for four wheeled carriages same is
true for slides
this slide shows that four horses can
pull enormous weight while one horse
will not be able to carry even one log
on its back
here is a picture of an Egyptian chariot
notice that the Pharaoh and rider are
standing on the axle which removes the
load from the horse also the large six
spoked will substantially reduce rolling
friction with the ground the horses
could run full speed with ease the
chariot was considered the battle tank
of its time it allowed Egyptians to
expand their empire
however there is a small catch while the
wheeled carriage has had big advantages
on the flat surface they have one major
disadvantage on the hilly roads when a
person carrying a load uphill there is a
component of its weight and the load
dragging him backwards multiplication of
this vector with velocity will not be
zero this time hence the power
requirement to carry the load and person
himself will be proportional with this a
passing vector higher the climbing angle
the higher will be the power requirement
the same thing happens to bicycles cars
and trucks while they are on an uphill
road they not only carry the load they
also carry the additional weight of the
equipment whether it's a car or a truck
we have to build flat highways whenever
it is possible by building tunnels or
bridges this will reduce fuel
consumption of cars and trucks
substantially by shortening the distance
and eliminating opposing force component
if trucks wear climbing
if you are using single two-wheeled cart
make sure that the center of gravity
passes through the axle of the cart or a
little bit or donkeys side as you can
see apposite shift of the load will put
poor donkey in very awkward position
in short the will takes the heavy load
from our shoulder and put all the weight
on the ground with overcoming slight
rolling resistance it enables us to
easily carry very heavy loads
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