Mr. Ward Week
7 2012
Amanda
Tauber
Investigate
and Designing
Friction:
Friction is a resistant force and occurs
when any two objects (solid, liquid or gas) come into contact with each other.
If an object is going one way – friction is pulling the object in the other
direction.
Friction can occur between any of the
following;
·
Two solid objects – the wheels of the kart and the surface of
the track, the gear kogs, the cooper wire and the fishing line, the wire
holding the tires together and the plastic tube etc.
·
Solid and Air – (Also known as air resistance), this can
occur anywhere in the direction the kart is travelling, when the kart pushes
forward, the air resistance will be pushing back on it.
·
Solid and Liquid – not as relevant to this design brief but an
example of this could be a person waddling in the water
·
Liquid and Air – once again, not as relevant to this brief,
but you notice this type of friction when water falls over a waterfall and is
turned into spray due to the friction with the air.
Friction is useful for;
·
Grip –the purposeful friction made into the wheels
in order for them to have grip on the floor. This stops the tires from
spinning. But in everyday uses, it is used in most items designed to move and stop
– anything from motorbikes to the grip on shoes.
·
Positive Air
resistance – though not entirely relevant
to this experiment, parachutes and similar inventions use air resistance to
work (to catch the air, allowing the rider to ‘float’)
·
Brakes – though our kart will not come with brakes,
friction is used to slow down and stop transport vehicles, (cars, motorbikes,
trains etc. ) by applying pressure (in simplest form) to the wheel which thus
causes the form of transport to slow down and stop.
Friction is a problem when;
·
The wear between
surfaces causes machernery to wear away and need replacement
·
Friction/air
resistance/drag is a waste of energy in machines for it has to create a
stronger force to counter the friction pushing back on it.
o Also
slows down moving objects
Ways to reduce friction;
·
Lubricating oil and
grease between surfaces
·
Wheels or ball
bearings or polystyrene balls to roll the surfaces past each other
·
Cushions of air (as
in hovercrafts for they avoid the friction with the ground)
·
Streamlined shapes to
keep air resistance at a minimum.
Velocity:
Velocity is the speed in which an object
is moving in relevance to the objective destination. Unlike speed which
describes how fast the object is moving, velocity gives a value on how fast the
object is going from point ‘a’ to point ‘b’
e.g. a car driving 50km/hr north.
A constant velocity must include a
constant speed and constant direction (straight path). Eg. A car is at a
constant speed of 40km/hr and is moving on a straight road – hence it has a
constant velocity
The velocity of an object will
accelerate or decelerate not only when the speed of the object changes, but if
the direction varies. I.e. if a car is turning a corner but, still is at a
speed of 30km/hr the velocity decelerates and then accelerates because the time
it takes to get closer to the objective goal varies as the car goes off the
direct course.
Velocity
is calculated by the equation, change in distance over change in time. Or
written as;
The velocity of my kart is;
Distance =
Time =
Therefore,
V = _/_
=
Kinetic Energy is the energy of
motion, any object that moves contains some amount of kinetic energy. Kinetic
energy is expressed by the equation: KE = ½ x m x v2 . This shows that the value of
kinetic energy relies on the mass and velocity (or speed) of the object.
Acceleration - Perform calculations to determine the average acceleration of your
vehicle.
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Materials
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Use
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Characteristics
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Properties
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Plywood
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The ‘chassy’ of my design. It keeps all the other materials used
to power my kart secure.
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Very light weigh however it is not ‘flimsy’ and does not break
easily. With a power saw, it is easy to c
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Approximently 4mm thick, 11cm long and a varing width of 4cm –
0.1cm.
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Small gear
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Attached to the motor, it interlocks with the larger motor,
thus, transferring the electrical energy within the motor into kinetic
energy; spinning the wheels.
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It is made up of a plastic and the cog has a small hole through
the center of it. This hole is a ‘push fit’ insuring that it is attracted to
the motor.
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It has 8 indents which interlock with the larger wheel and an
approximate 0.3cm diameter.
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Large Gear
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Attached to the back Axel, this large gear. Interlocking with
the smaller gear, this large gear turns the wheel.
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“as above”
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Motor with +ive and –ve
wires
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To covert the electrical energy into kinetic energy
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It is make of metal with a plastic cap on one end of the motor.
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Has a metal point that the small cog is attached to. Also has
coloured positive and negative wires, pre soldered to the opposite end.
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X2 Large wheels
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To transfer the kinetic energy from the motor and use that
energy to drive the kart forward
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A circular diameter with the grip and tire cap removed. Has an
opening on the inner side. Alowing the axel to press fit – so it does not
slide off.
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The tire came with a cap and grip tire, but I had removed them.
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x2 small wheels
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To move the kart across the track.
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x2 strands of copper
wire
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To keep the kart running along the track in a straight line
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The copper wire is dutile, allowing it to be bend and manipulate
into different shapes and forms
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It only consists of the copper wire
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Battery Pac with +ive and –ve
wires
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To transfer the chemical energy through to electrical energy
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Normal characteristics of a x2 battery pac
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The battery pac and a positive and negative wire.
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x1 Switch with +ive and –ve
wires
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To have easy access to open and close the circuit.
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A flick switch.
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has coloured positive and negative wires, pre soldered to the
opposite end.
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x2 4cm plastic tube
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To attach the axel to the chassy whilst allowing the axel to
spin
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A hollow plastic cylinder
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transparency,
flexibility, elasticity, permeability, water resistant, electrical resistance
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x1 7.2 (approx.) axel
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To attach each of the two wheels together and to enable the gear
to successfully turn the wheel.
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Metal cylinder
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It is hard, ensuring it does not bend easily
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Planning – A documented series of
ideas showing the development of your final solution.
Sequencing – This is for my final
design (using plywood)
1.
Making the Chassy
a.
Draw the chassy (expressed in image *final* as
shown above in planning) with correct measurements and all lines shown, adding
2mm to each side.
b.
Using the “jigger jagger” cut the shape of the
chassy out.
c.
Sand all sides of the chassy until smooth. Sand
also the front point of the chassy, allowing a smooth rise from the bottom to
the top of the chassy.
2.
Producing the Front
Wheels
a.
Measure and cut the plastic tube and axel to
scale. (note. When cutting the plastic
tube, use pliers to reopen the end of the tube that was closed via the cutting
of the tube)
b.
Remove the wheel caps from the small wheels
c.
Hammer one point of the axel into the first of
the small wheels, slide the plastic tube onto the axel.
d.
Hammer the final small wheel onto the end.
(make sure you leave enough room between the plastic tube and wheels to ensure
that the wheels spin)
e.
Leave for later
3.
Producing the Back
wheels,
a.
Follow steps 2a-c with back wheel measurements
b.
Hammer the large gear on (top hat first). Using
a cog on the side of the workbench and hammering the axel through the gap.
c.
Hammer the other wheel onto the end of the axel
4.
Using hot glue, attach the battery pack to the
very end of the chassy, with both wire’s facing the end of the chassy.
5.
Attaching the wheels
a.
Glue both sets of wheels on by applying a line
of hot glue over the lines ruled onto the chassy as done in step 1a, and attach
the white plastic tube to the hot glue.
b.
Allow to set before gluing the other wheel
6.
Attaching the motor
a.
Apply hot glue to the bottom of the motor
b.
Press the motor onto the bottom of the chassy
and slide the motor until the small gear wheel interlocks with the large gear
wheel
7.
Hot glue the switch to the back of the chassy.
8.
Wiring up the elements
a.
Using the wire cutters, cut the wires to a length
in which the least wire is hanging loose
b.
Using the soldering iron heat up the connection
points between the two wires, once hot, melt some _____ onto the connection
c.
Repeat for all links
Production Images (from
Blog)
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30th July
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13th august
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Evaluate
Aspects of Design –
Function. Based on your calculations critically
evaluate your vehicle’s performance and comment on the effectiveness of
your solution? What is not good or in need of attention with regard to your
solution?
Future improvements – State any
improvements that could be made if you had the opportunity to redesign the
solution i.e. ways to further eliminate friction and resistance forces.
Other vehicles: Comment on the
successes and / or failures of other vehicles.
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