Video of our car in action
Sydney and me with
Clarence (car) after our timed run.
Clarence the three
wheeled monster clocked in a t covering five meters in 4.23seconds taking 4th
place
How did Newton’s Laws apply to the
performance of the car?
·
The first law states that objects at
rest will say at rest, and objects in motion will stay in motion unless acted
on by an outside force. This law is used in the car as the spring acts as the outside
force to start the car, and then by utilizing the smallest amount of friction
an outside force the car will continue to roll forward.
·
The second Law states that acceleration
equals force over mass. This is seen in the car in the lever arm of the spring,
as well as the accounting for mass. Since the spring creates a set amount of torque
creating a longer lever arm decreases force, but as this happen the longer
lever arm moves farther distance. A
shorter lever arm uses more force to produce the same torque, and is therefore
faster. Weight and mass on the care is a thin line, on one side it is not heavy
enough, and on the other it is creating too much friction with the ground and
will not work.
·
The third law states that every action
has an equal and opposite force. This is seen in the car with the wheels, as
wheels push car back ground pushes car forward. The car creates more friction
forward then backward and therefore accelerates on to the track.
Which
Part of your car relied on friction? How did you utilize it?
Our car relied on friction in the wheels, so that they
would hold traction and be able to move on the ground. We accomplished this by
using balloons and stretching them around so that they would be covered in
rubber, and therefore very sticky. There are two ways to change friction one by
adding weight so that the surfaces are pushed harder together, or changing the
nature of the surface, which is what we chose.
How
did the size of the wheels affect the cars performance?
I think we chose
wisely in choosing a wheel which was not to large or small. We used CD’s, and
their large diameter was very helpful because each rotation covered much more
ground than a smaller wheel such as bottle cap. This is seen in the real world
with fly reels, as larger reels are made in a large arbor which has a much
greater diameter than mid arbors which only pick up a fraction of the line in
each rotation. I think our choice of using a wheel which was not very thick was
very beneficial, as it is comparable to a road bike tire and that of a mountain
bike.
What
did the size of the wheels mean for torque, and rotational inertia?
Larger
diameter wheels mean larger torque, since the wheel radius acts as a lever arm.
A larger radius means that the weight is going to be spread farther away from
the axis of rotation, and therefore have a larger rotational inertia. Though a
larger diameter wheel allows you to cover more distance in a single rotation it
is also much harder to get going due to its larger rotational inertia.
Why
can’t we calculate the amount of work the spring does on the car? Why can’t we
calculate the amount of potential energy stored in the spring, and the amount
of kinetic energy used? Why can’t we
calculate the force of the spring on the car?
We cannot calculate the amount of work the spring does on
the car since the spring is not parallel with the ground, and therefore no work
is done. We cannot determine potential energy since work = change in kinetic energy,
and kinetic energy = potential energy, and since work cannot be determined nor
velocity since it is constantly changing finding the energy is impossible. We
cannot find the force because we cannot calculate work, which would allow us to
solve for force since work = Force (Distance).
Reflection
Our design did not change at all between drafting and
finished product. The only major change was the difference in use of robotics
fasteners to on the forward wheel The change was prompted by the hot glue on
the forward axle from becoming dislodged causing us to lose our front wheel.
The
only major setback we experienced with performance was the tendency of the car
to get stuck in the rut of the floor boards, and to eventually stop over a foot
short. To address this we put masking tape on our front wheel so that the
surface would be wider eliminating the ability of it to sink into a rut.
.
To make my car go faster in the future I would use mono filament instead of a
braided yarn as it would stack better on the axle allowing for more line under
tension so that you will get more rotations on the axle allowing for a farther
distance to be reached.
Next
time I do a building project I want to spend more time tinkering with a working
project so that I can tweak it to be better. In both robotics and this project
I felt that we built a decent product but did not meet its full potential due
to lack of time experimenting with it.
