Jouri surfaces. They reduce friction and provide leverage.

Jouri
AlSharhan

January
19, 2018

Phase
1 Exercise

Bicycle Wheel

Wheels
are used to provide a more reliable way of transportation rather than having to
drag things through rough surfaces. They reduce friction and provide leverage.
(“How Do Wheels Work? | Science of
Wheels and Axles.” ) Bicycle
wheels are normally over 20 inches in diameter, which is taller than most car
wheels.

The wheels support the
rider’s entire weight, mainly due to the way they are formed. The wheels of
bikes are made of a strong hub, a thin rim, and approximately 24 spokes in high
tension. Spokes are the connecting rods found between the bicycle
hub and the rim. (“Bicycle Spokes.”). The use of spokes
rather than metal such as cars allows bicycle wheel to be both strong and
lightweight and to reduce drag.

The  way spokes are connected between the hub and
rim is important. A bike wheel is generally in tension because the spokes are
pulled tight. Since the spokes criss-cross from the rim to the opposite side of
the hub, the wheel is not as fragile as it appears. When you sit on a bike,
your weight pushes down on the hubs, which stretch some of the spokes
unevenly.  The spokes are what prevents
buckling from occurring in the wheel when you sit on the bike.

The spokes bear the weight
unevenly: the few spokes that are near the vertical bear much more load than
the others. As the wheel rotates, other spokes move closer to the vertical and
begin to take more share of the strain. The constant cycle of sharing more
strain and then relaxing as the wheel rotates eventually leads to having one of
the spokes failing.  After that, a domino
effect occurs in which the other spokes will have to carry more loads to
compensate for the failed spoke making them more likely to fail too which as a
result makes the wheel buckle. (“Bicycle
Science – How Bikes Work and the Physics behind Them.”)

 

                                                                 

 

 

 

 

 

 

 

 

Geodesic Dome

Geodesic
domes are structures that look like half spheres that are made up of many
triangular supports. They come from geodesic designs, which are based on a
polyhedron. A polyhedron is a three-dimensional solid that is made up of many faces.
Examples of polyhedrons are pyramids and prisms. A common polyhedron that is
used for geodesic dome designs is called an icosahedron, which is a solid shape
composed of 20 flat faces. Each face is an identical equilateral (all sides are
equal) triangle. Rotate the edges of those triangles slowly toward an imaginary
center and eventually you wind up with a rough version of a sphere, called a
geodesic sphere. Cut that sphere in half and you have an approximation of a
geodesic dome (Chandler).

The
pairing of domes with triangles, makes one extremely durable structure.
Triangles are the strongest shape because they have fixed angles. In other
words, pressure applied to one edge of a triangle, will evenly distribute the
force on the other two sides, which then transmits pressure to nearby
triangles. That distribution of pressure is how geodesic domes efficiently
distribute stress along the entire structure (Chandler).     

The
manner in which a braced dome behaves depends on the configuration of the
members. Fully triangulated domes, such as geodesic domes, have a high
stiffness in all directions and are kinematically stable.  If it is not fully triangulated, it is not
kinematically stable when idealised as a truss and stiffnesses varies in different
directions.Kardysz et al., 2002.

The forces in a geodesic network are an
equilibrated combination of tension and compression. Tension forces are global
and continuous, while compression forces are local and discontinuous.
Buckminster Fuller coined the term tensegrity, a portmanteau of tensional
integrity, to convey the concept of coherence and resilient elasticity of
geodesic networks.

 

 

                                   

 

 

 

 

 

 

 

 

 

 

 

 

 

Ladder

 

A ladder
is a structure that consists of two uprights lengths of wood or metal with a
series of bars between them. Its purpose is to reach higher elevations safely.
Over its lifetime the ladder is expected to carry its own weight, the person
climbing it, and the object that the person might carry with them.                                      

There are many forces that
act on a leaning ladder when it is in use. First, there are two upward vertical
forces. There is an upward vertical contact force from the floor which supports
the ladder and a vertical upward friction force from the wall where the ladder
leans against it. Combined , these two forces are able to support the weight of
ladder. The weight of the ladder acts through the center of gravity in the
middle of the ladder, so it exerts zero torque. However, all the remaining
forces do not act through the ladder’s center of gravity and therefore exert
torque. The summation of all torques results in zero.           

Second, there is a
horizontal force from the wall onto the ladder where they meet. Another
horizontal force is caused by the friction between the ladder and the floor.
The sum of these forces results in zero making the ladder stable.

                       

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fern

 A fern is a nonflowering vascular plant that
possesses roots, stems, and complex leaves and that reproduce by spores. They
belong to the lower vascular plant division, Pteridophyta, having leaves
usually with branching vein systems (Walker). In its lifetime, ferns can
encounter many loads that they are supposed to carry due to the environment
they live in.     

A better
understanding of the fern anatomy helps clarify how ferns carry loads. Just
like other plants, ferns have roots, stems, and leaves. These parts, however,
have names that are specific to ferns.

The
Rhizome or Rootstock is the part of the plant that is responsible for producing
roots. They can be thin or thick. They act as the foundation of the fern and
often indicate the growth form of the fern. Rootstock is much like the
foundations used in buildings.

The stem
is what connects the root of the plant to the leaves. Its main function is
to  support the fern and keep it
standing.

The leaf
or frond is what carries the leaflets – the smaller leaves that branch out. The
leaflets are the parts of the frond that are divided. Due to the nature of the
leaves branching out forces that act on them branch out as well (Bowe).                                        

                             

                       

                                   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Work Cited

 

 “Bicycle Science – How Bikes Work and the
Physics behind Them.” Explain That Stuff,
13 June 2017, www.explainthatstuff.com/bicycles.html.

 “Bicycle Spokes.” Materials Engineering – Purdue University,
engineering.purdue.edu/MSE/aboutus/gotmaterials/Sports/lindamood.html.

Bowe, Audrey. “All About Ferns: A
Resource Guide”

http://blogs.cornell.edu/naturalistoutreach/files/2013/09/Fern-Guide-27sra8m.pdf

 

 Chandler, Nathan. “How Geodesic Domes Work.” HowStuffWorks Science, HowStuffWorks, 13
Sept. 2011, science.howstuffworks.com/engineering/structural/geodesic-dome.htm.

 “How Do Wheels Work? | Science of Wheels and
Axles.” Explain That Stuff, 24 Oct.
2017, www.explainthatstuff.com/howwheelswork.html.

 “Ladder.” Dictionary.com,
Dictionary.com, www.dictionary.com/browse/ladder?s=t.

 Walker, Warren F., et al. “Fern.” Encyclopædia Britannica, Encyclopædia
Britannica, Inc., 18 Oct. 2016, www.britannica.com/plant/fern.

 www.quora.com/What-forces-are-present-when-a-ladder-leans-on-a-wall.

 

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