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Running Head: PHYSICS SHORT ESSAYS

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Physics Short Essays
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PHYSICS SHORT ESSAYS

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Classical Physics

The fact that a plane cannot fall to the ground like a large metal projectile is an
application of Newton’s third law of motion. Airplane wings are designed to take the shape of an
airfoil (Sforza, 2014). An airfoil has a curved upper surface and a flat lower surface. Therefore,
as the plane flies through the sky, the airfoil deflects the air thereby causing a difference in
pressure above and below the wings. Precisely, as the airplane thrusts forward, the curved upper
surface of its wings lowers the air pressure immediately above the wing, causing an upward lift
(Sforza, 2014).
Air moves in a straight line. However, the curved upper surface of the wings pulls it
around and then downwards. This makes the air to stretch out over an effectively bigger volume
than the lower surface of the wings. Air molecules immediately above the curved surface of the
wing are spread over more space than those moving on the lower surface of the wing (Sforza,
2014). Consequently, since the air molecules above the curved surface are spread over a larger
volume of space, the pressure immediately above the curved surface becomes lower than that
below the flat surface of the wing. The difference in air pressure above and below the wing also
causes a huge difference in air speed (Sforza, 2014). The result is that a dynamic lift results that
causes the airplane to move upward against gravitational force.
As Newton’s third law states, for every action force there is an equal and opposite
reaction force (Zimba, 2009). Therefore, if the air gives an upward force to the airplane in the
form of a dynamic lift, the plane produces an equal and opposite downward force to the air. To
generate the downward force on the air, the airplane uses its airfoil-designed wings to push the
air downward behind it. This is particularly effective since the wings are inclined and not
oriented perfectly horizontal to the plane. The wings are particularly tilted back slightly in order

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that they hit the air at an angle of attack (Sforza, 2014). Consequently, the tilted wings push
down both the fast-moving air above the wind and the slower air beneath them, producing an
upward lift. The fact that the upper surface of the wing is curved and the lower surface of the
wing is straight yields even more lift.
Generally, wings are forced upwards since they are tilted. The tilt forces airflow
downwards, causing an upward push on the wings according to Newton’s third law of motion
(Sforza, 2014). The action of the wings through its strategic tilt is called an angle of attack. In
order to achieve an angle of attack, the trailing edge of the wing must be sharp. Additionally, the
edge of the wing must be aimed diagonally downwards to create the lift (Sforza, 2014). The
upper and lower surface of the wing are primarily used to deflect the wing. As such, the wings
are designed in the shape of the airfoil to cause differences in pressure and speed of airflow that
yields sufficient lift for the plane. The amount of upward lift depends on the speed of the air and
the air density (Sforza, 2014). For the plane to generate more lift, the airplane must increase its
speed or increase the angle of attack of its wings.
Use of Newton’s second law: When a truck and a car are pushed with the same force, the
car moves with a higher acceleration than the truck.
Electricity, Magnetism, and Light
It is a matter of common knowledge that the voltage range for domestic use is between
220 – 250V. However, the charging station with the USB adaptor port provides its users with an
electricity of 5V. This low voltage output is achieved using a step-down transformer. A stepdown transformer is a transformer in which the output voltage is less than the input voltage
(Bakshi & Bakshi, 2009). In a step-down transformer, the number of turns in the primary core is
greater than the number of turns on the secondary core. A step-down transformer works on the

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principle of magnetic induction. Magnetic induction is defined by Faraday’s law which states
that when the magnetic flux linking a circuit changes, an electromotive force is induced in the
circuit proportional to the rate of change of the flux linkage (Bakshi & Bakshi, 2009). According
to the principle of magnetic induction, when a voltage is applied to the primary coil, it
magnetizes the iron core which in turn induces a voltage on the secondary coil of the
transformer. In this way, the voltage transforms from the primary to the secondary windings of
the transformer. The voltage induced between the two windings is determined by the number of
turns in the primary and secondary windings – turns ratio (Bakshi & Bakshi, 2009). Therefore,
the voltage output of the step-down transformer depends on the turns ratio of the primary and
secondary coil. Evidently, since the transformer works on the principle of magnetic induction,
then the adaptor operation is related to both electricity and magnetism.
The scenario also mentions an LED next to the phone’s screen. An LED is a light
emitting diode and works on the principle of electroluminescence. Accordingly, when a
sufficient amount of voltage is applied across the LED, electrons recombine with holes and in the
process release energy in the form of photons (light). The operation of the LED is related to
electricity and light.
From the scenario, it is apparent that Italy’s electricity was generated through the burning
of fossil fuels. Usually, the heat generated from the burning of fossil fuels is used to turn water
into steam. The steam generated is usually under high pressure and is used to rotate turbines or
generator. Therefore, in this case, mechanical energy in the form of heat is converted to kinetic
energy which is in turn converted to electrical energy by the use of a generator. Usually, a
turbine is used exert rotary motion on the generator which in turn converts the mechanical
energy into electricity. A generator works on the principle of electromagnetic induction. The

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principle of electromagnetic induction is defined by Faraday’s law which states that whenever a
conductor is placed in a varying magnetic field, EMF is induced and that the induced EMF is
equal to the rate of change of flux linkages (Bakshi & Bakshi, 2009). Since the electricity in
Italy’s is generated by involving the principle of electromagnetic induction, then the scenario is
related to electricity and magnetism. It is also stated in the scenario that Mandy decided to use
the portable solar charger. A solar charger consists of photocells that use photons of light to
generate electricity. Evidently, this part of the scenario is related to electricity and light.
Maxwell’s research led to the development of modern color photography. Maxwell
invented the trichromatic process that produced the first color photography.
Einstein’s Physics
From the scenario, it is stated that “…she knew that in fact, she was a tiny bit younger
than her compatriots back home, thanks to traveling at hundreds of miles per hour.” The
implication of the statement here is that time slows down as an observer moves at a higher speed
and hence becomes slightly younger than a stationery observer. This is related to Einstein’s
theory of relativity. Einstein’s theory of general relativity applies to objects that are accelerating
with relative to each other (Einstein, 2009). In this theory, Einstein observed that time does not
pass at the same rate for every observer but rather passes at a rate relative to the motion of the
observer. Precisely, Einstein stated that a fast-moving observer measures the passing of time
more slowly that a relatively stationary observer observes time (Einstein, 2009). Time slows
down or speeds up depending on how fast one moves relative to another observer. Therefore, an
observer moving at a speed approaching the speed of light would age much slower than another
observer who is relatively stationary back at home (Einstein, 2009). This, Einstein called time
dilation. Therefore, from the scenario, Mandy is moving at a relatively higher speed than her

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compatriots back at home and hence her time moves slightly slowly than her compatriots.
Consequently, she ends up becoming slightly younger than her compatriots.
From the scenario, it is clear that neither the speed and height of the airplane were
noticeable to Mandy. The implication here is that Mandy did not notice that the airplane was
moving at a high speed. Mandy was actually part of the airplane and was moving with the same
speed as the airplane though according to her she was just seated. Since there was no significant
relative motion between her and the airplane, she could not notice the high speed with which the
plane was moving. Since the concept is related to the aspect of relative motion, then it is related
to Einstein’s theory of relativity.
From the scenario, it is stated that as Mandy stretched, her bones creaked as though she
was old. The implication her is that stretching her body was slightly difficult on the moving
plane than when she was stationary. This fact, again is related to Einstein’s theory of general
relativity. In his theory, Einstein stated that mass and energy are different manifestations of the
same thing (Einstein, 2009). Through this argument, Einstein developed the equation E=mc2.
The implication of the equation is that a fast-moving object appears to have increased mass
relative to a slow-moving one. The explanation for this is that increasing an object’s velocity
increases its kinetic energy and, hence, its mass (since mass is equal to energy) (Einstein, 2009).
This concept in E...