Physical Science 2nd Quarter

Astronomy

It is the science that studies the universe.

Aristotle

He concluded that the earth was round because it always cast a curved shadow when it passes between the sun and the moon.

Eratosthenes

An ancient Greek mathematician, calculated that the  earth’s circumference is 39,000 kilometers very close to our own modern measurement of 40,075 km.

Geocentric Model

In this model, the moon, sun, and the known planets – Mercury, Venus, Mars, Jupiter and Saturn – orbit earth.

Aristarchus

He was the first Greek to believe in a sun-centered, or heliocentric, universe.

Claudius Ptolemy

He is our main source for what the ancient Greeks knew about astronomy. He also attempted to explain retrograde motion, or how each planet appears sometimes to stop in the night sky, reverse direction, and then resume eastward motion.

Nicolaus Copernicus

He proposed the heliocentric model of the solar system: Earth is a planet and all planets of the solar system revolved around the sun at its center.

​Johannes Kepler

He was Brahe’s assistant, and later the first important modern astronomer. He applied mathematics to Brahe’s findings and discovered Three Laws of Planetary Motion.

First Law (Law of Ellipses)

The path of each planet around the sun is an ellipse, with the sun at one focus.

Circle

It is a closed curved shape that is flat. In this, all points on the this are equally distant from the center of it.

Second Law (The Law of Equal Areas)

It determined that a planet travels most rapidly when it comes closest to the Sun and moves slowest when farthest away.

Third Law (The Law of Harmonies)

It gives the precise relation between the distance of a planet from the Sun and how fast it completes an orbit, using Astronomical Units (AU).

Isaac Newton

An English scientist and mathematician famous for his discovery of the law of gravity also discovered the three laws of motion.

1st Law

Laws of Motion: An object at rest tends to stay at rest and an object in motion tends to stay in motion unless acted upon by an unbalanced force.

Types of Friction

Sliding Friction

Rolling Friction

Fluid Friction

Static Friction

2nd Law

Laws of Motion: Force equals mass times acceleration.

Acceleration

A measurement of how quickly an object is changing speed.

Force

It is directly proportional to mass and acceleration.

3rd Law

Laws of Motion: For every action there is an equal and opposite reaction.

Inertia

The tendency of an object to resist changes in its state of motion.

Velocity

The rate of change of a position along a straight line with respect to time.

Motion

It is an object’s change in position with respect to time.

Natural Motion

It is when an object will move and will eventually return to its natural state depending on the composition that the object is made of. An object made of material similar to air will return to the air.

Violent Motion

An object will move if an external force such as pushing or pulling is applied to it.

Projectile Motion

The motion of an object is parallel to the ground until it is the object’s time to fall back into the ground.

Impetus

A force or energy that permits an object to move. 

Horizontal Motion

An object in motion, if unimpeded, will continue to be in motion, and an external force is not necessary to maintain the motion. 

Vertical Motion

In the absence of resistance, objects would fall not depending on their weight, but in the time of fall.

Projectile Motion

It is a combination of uniform motion in the horizontal direction and uniformly accelerated motion in the vertical direction. If it is not impeded, it will continue to move even without an applied force.

Giordono Bruno 

He was an ordained priest by the Catholic Church and believed in atoms.