Physics Concepts: Motion, Vectors, and Scalars
Vector-Scalar product: The product of a scalar with a vector only changes the magnitude of the vector, but does not mess with direction: n(A) = nA
Dot product (Scalar product): This kind of product between two vectors is also called scalar product because its result is a number that means a scalar quantity. It is defined as: A. B = |A||B| cos θ
Cross product (Vector product): This kind of product between two vectors is also called scalar product because its result is a vector quantity. It is defined
Read MoreScientific Revolutions: Copernicus, Newton, Einstein
What is a Scientific Theory?
A scientific theory is a set of ideas or hypotheses (assumptions) that satisfies two conditions: it must align with observations or recorded data, and it must not contradict fundamental concepts.
The Copernican Revolution: Sun-Centered Universe
For about 2,000 years, from the time of Aristotle until after Columbus’s voyages to the New World, it was believed that the Earth was the center of the universe (the geocentric theory). The shift to the Copernican heliocentric theory,
Read MoreUniverse, Stars, and Galaxies: A Cosmic Journey
Spectra
Isaac Newton discovered that sunlight, when incident on a glass prism, decomposes into colored stripes. This rainbow is called the spectrum of light. Technical improvements revealed black lines within the spectrum. The Sun, being the nearest star, provides a light spectrum that offers information about its elemental composition. By comparing the black lines in the Sun’s spectrum with those of hydrogen and helium, we can conclude that the Sun’s outer layers are primarily composed of these
Read MoreFundamental Forces: Gravity, Electricity, and Magnetism
Fundamental Forces in Nature
Gravitational force and electromagnetic force are two fundamental forces found in the natural world.
Both are action-at-a-distance forces because their effects can be felt without direct contact.
Other types of fundamental forces include the strong nuclear force and the weak nuclear force.
Kepler’s Laws of Planetary Motion
Johannes Kepler described the motion of planets with three laws:
- First Law: Planets move around the Sun in elliptical, almost circular, orbits. The aphelion
Understanding Kinematics: Key Concepts and Forces
What does kinematics study? The movement of bodies.
Concepts Needed to Study the Movement of a Body
- Reference Frame: An oriented straight line in which motion occurs. It presents an origin and an axis.
- Position: The distance between the object and the origin of the reference frame.
- Displacement: The difference between any two positions.
When does a body move? When it varies its position with respect to the origin of the reference frame.
What is velocity? The measurement of the rate at which bodies move.
Read MoreUnderstanding Sound: Amplitude, Frequency, and Wave Behavior
Bigger Amplitude = More Energy. More Energy = Louder.
Sound dissipates (lessens) as it travels away from the source. This intensity can be measured. Intensity has units of watts/meter2 or the more commonly used decibels (dB).
Frequency = How fast the medium is vibrating. Measured in the number of waves per time period. More generally, frequency (or pitch) is measured in Hertz (Hz). Human ears can detect pitches from 20 Hz to 20,000 Hz.
Period is measured in seconds and is related to frequency: T =
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