Natsci1 Exercise # 1

EXERCISE 1. PRECISION AND ACCURACY

 

Objectives:

1. To know the difference between precision and accuracy
   
2. To be able to compute precision and accuracy
   
3. To deduce possible errors in experiments
   

 

Materials: Ruler

 

Procedure

1. Measure the length and width (cm) of the table assigned to you. Each student should have their own turns in measuring without relying or copying the data of your group mate.
   
2. Compute the area of the table (expressed units in square centimeters). Record your data on Table 1.1
   
3. Compute for the deviation of your AREA table using the formula
   

   d=Ū-Ui            where Ū is the AVERAGE AREA
   

                   and Ui are the INDIVIDUAL CALCULATED AREA
   

    After you get the deviation, compute for the AVERAGE DEVIATION (AD = d1+d2+d3….+dn/n)

 

1. Get the True Value (TV) of your table from your teacher and compute for the INDIVIDUAL PERCENT ERROR (%E)
   

   %E = /TV-OV/ x 100
   

       TV
   

 

        Where TV = True Value

            OV = Observed Value (calculated area)

1. Get the % Error of the other groups and compare it with your % Error.
   

Data/Illustration

Table 1.1 Dimensions of the table

Student (Ui)	Length (cm)	Width (cm)	Area (sq cm)

 

Table 1.2 Deviations and Percentage Error within the Group

Student (Ui)	Deviation (d)	Ave. Dev (AD)	% Error (% E)	Ave % E (APE)

 

 

 

Table 1.3 APE of Other Groups

Group Number	APE

 

Guide Questions for Discussions

1. What is precision? What is accuracy?
   
2. What is the difference between precision and accuracy?
   
3. What is the basis if your measurements are precise? If your measurements are accurate?
   
4. Which student within your group has the most precise measurement? Has the most accurate? Why?
   
5. Which group has the most accurate measurements and why?
   
6. Site some possible errors encountered or committed in the experiments? How will you work out on these errors?
   
7. Which is more important in measurements; precision or accuracy? Why?
   

 

 

*Deadline for Submission of Lab Reports will be on TUE 5pm (for MWF Natsci Class)

And Mon 5 pm (for TTH Natsci Class)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Rlp2011

Planets in the Solar System

The Terrestrial Planets
The terrestrial planets are the four innermost planets in the solar system, Mercury, Venus, Earth and Mars. They are called terrestrial because they have a compact, rocky surface like the Earth's. The planets, Venus, Earth, and Mars have significant atmospheres while Mercury has almost none.

Mercury
As you travel outward from the Sun, Mercury is the closest planet. It orbits the Sun at an average distance of 58 million km. Mercury is airless, and so without any significant atmosphere to hold in the heat, it has dramatic temperature differences. The side that faces the Sun experiences temperatures as high as 420 ºC, and then the side in shadow goes down to -173 ºC. Mercury is also the smallest planet in the Solar System, measuring just 4879 km across at its equator.
Mercury has only been visited two times by spacecraft. The first was Mariner 10, back in the mid 1970s. It wasn’t until 2008 that another spacecraft from Earth made a close flyby of Mercury, taking new images of its surface with Caloris Basin as its largest surface (1350 km in diameter). It revolves around the sound for 0.24 Earth year (or almost 3 months)

Venus
Venus is the second planet in the Solar System, and it’s an almost virtual twin of Earth in terms of size and mass. Venus orbits at an average distance of 108 million km, and completes an orbit around the Sun every 224 days. Apart from the size, though, Venus is very different from Earth. It has an extremely thick atmosphere made almost entirely of carbon dioxide that cloaks the planet and helps heat it up to 460 °C. If you could stand on the surface of Venus, you would experience 92 times the pressure of Earth’s atmosphere, with incredibly high temperatures, and poisonous clouds of carbon dioxide and sulfuric acid rain.
Several spacecraft have visited Venus, and a few landers have actually made it down to the surface to send back images of its hellish landscape. Even though there were made of metal, these landers only survived a few hours at best. Maxwell Montes is Venus’ highest point of surface (17 km) and the planet’s revolution is 0.62 Earth year.

Earth
Earth is our home; the third planet from the Sun. It orbits the Sun at an average distance of 150 million km. Earth is the only planet in the Solar System known to support life. This is because our atmosphere keeps the planet warm from the vacuum of space, but it’s not so thick that we have a runaway greenhouse effect. The Earth has a solid core of iron surrounded by a liquid outer core that generates a magnetic field that also helps protect life on Earth from the radiation of space.
No planet in the Solar System has been studied as well as Earth, both on the ground and from space. Thousands of spacecraft have been launched to study the planet, measuring its atmosphere, land masses, vegetation, water, and human impact. It revolves around the Sun for 365.25 days. Mount Everest is the highest peak (8 km above sea level)
Earth has only a single moon… the Moon.

Mars
The 4th planet from the Sun is Mars, the second smallest planet in the Solar System. It orbits the Sun at an distance of 228 million km. You might think Mars is large, but it’s a tiny world, with about half the diameter of Earth, and just 1/10th the Mass. If you could stand on the surface of Mars, you’d experience about 1/3rd Earth’s gravity. Mars has almost no atmosphere to help trap heat from the Sun, and so temperatures can plunge below -140 °C in the Martian winter. Even at the height of summer, temperatures can get up to 20 °C in the day – just barely shirt sleeve weather.
Mars has been heavily studied by spacecraft. There are rovers and landers on the surface, and orbiters flying overhead. It’s probably the likeliest place to search for life in the Solar System. It has a 24-km peak surface called Olympus Mons and revolves around the Sun for 1.88 Earth years.
Mars has two tiny asteroid-sized moons: Phobos and Deimos.

The Jovian Planets
Jupiter, Saturn, Uranus, and Neptune are known as the Jovian (Jupiter-like) planets, because they are all gigantic compared with Earth, and they have a gaseous nature like Jupiter's. The Jovian planets are also referred to as the gas giants, although some or all of them might have small solid cores.

Jupiter
Mighty Jupiter is the biggest planet in our Solar System. It’s so large, in fact, that it has 2.5 times the mass of all the rest of the planets in the Solar System combined. Jupiter orbits from the Sun at an average distance of 779 million km. Its diameter at the equator is 142,984 km across; you could fit 11 Earths side by side and still have a little room. Jupiter is almost entirely made up of hydrogen and helium, with trace amounts of other elements.
Jupiter has been visited by several spacecraft, including NASA’s Pioneer and Voyager spacecraft; Cassini and New Horizons arrived more recently. Only the Galileo spacecraft has ever gone into orbit around Jupiter, and it was crashed into the planet in 2003 to prevent it from contaminating one of Jupiter’s icy moons. Jupiter has a faint ring.
Jupiter has the most moons in the Solar System – it has 63 moons at last count.

Saturn
Saturn is the 6th planet from the Sun, and the 2nd largest planet in the Solar System. It orbits the Sun at an average distance of 1.4 billion km. Saturn measures 120,000 km across; only a little less than Jupiter. But Saturn has much less mass, and do it has a low density. In fact, if you had a pool large enough, Saturn would float!
Of course, the most amazing feature of Saturn is its rings. These are made of particles of ice ranging in size from grains of sand to the size of a car. Some scientists think the rings are only a few hundred million years old, while others think they could be as old as the Solar System itself.
Saturn has been visited by spacecraft 4 times: Pioneer 11, Voyager 1 and 2 were just flybys, but Cassini has actually gone into orbit around Saturn and has captured thousands of images of the planet and its moons.
And speaking of moons, Saturn has a total of 60 moons discovered (so far).

Uranus
Next comes Uranus, the 7th planet from the Sun. It orbits the Sun at an average distance of 2.9 billion km. Uranus measures 51,000 km across, and is the 3rd largest planet in the Solar System. While all of the planets are tilted on their axes, Uranus is tilted over almost on its side. It has an axial tilt of 98° with a narrow faint ring made up of rocky or carbonaceous material. Uranus was the first planet to be discovered with a telescope; it was first recognized as a planet in 1781 by William Herschel.
Only one spacecraft, Voyager 2, has ever visited Uranus up close. It passed by the planet in 1986, and captured the first close images.
Uranus has 27 known moons.

Neptune
Neptune is the 8th and final planet in the Solar System, orbiting at an average distance of 4.5 billion km from the Sun. It’s the 4th largest planet, measuring about 49,000 km across. It might not be as big as Jupiter, but it’s still 3.8 times larger than Earth – you could fit 57 Earths inside Neptune. Neptune is the second planet discovered in modern times. It was discovered at the same time by both Urbain Le Verrier and John Couch Adams.
Neptune has only ever been visited by one spacecraft, Voyager 2, which made a fly by in August, 1989.
Neptune has 13 known moons and the planet has narrow rings that contain concentrations of icy particles called ring arcs.

Dwarf Planets
In 2006 the International Astronomical Union (IAU) approved a new classification scheme for planets and smaller objects in our Solar System. Their scheme includes three classes of objects: "small solar system bodies" (including most asteroids and comets), the much larger planets (including Earth, Jupiter, and so on), and the new category of in-between sized "dwarf planets".
There are currently five official dwarf planets. Pluto, formerly the smallest of the nine "traditional" planets, was demoted to dwarf planet status. Ceres, the largest asteroid in the main asteroid belt between Mars and Jupiter, was also declared a dwarf planet. The three other (for now!) dwarf planets are Eris, Makemake, and Haumea. Pluto, Makemake, and Haumea orbit the Sun on the frozen fringes of our Solar System in the Kuiper Belt. Eris, also a Trans-Neptunian Object, is even further from the Sun.

rlp2010 (source:IAU)

Stars

Types of Galaxy

Types and Classification of Galaxies

There are three main types of galaxies: Elliptical, Spiral, and Irregular. Two of these three types are further divided and classified into a system that is now known the tuning fork diagram. When Hubble first created this diagram, he believed that this was an evolutionary sequence as well as a classification.

Elliptical Galaxies

Elliptical galaxies are shaped like a spheriod, or elongated sphere. In the sky, where we can only see two of their three dimensions, these galaxies look like elliptical, or oval, shaped disks. The light is smooth, with the surface brightness decreasing as you go farther out from the center. Elliptical galaxies are given a classification that corresponds to their elongation from a perfect circle, otherwise known as their ellipticity. The larger the number, the more elliptical the galaxy is. So, for example a galaxy of classification of E0 appears to be perfectly circular, while a classification of E7 is very flattened. The elliptical scale varies from E0 to E7. Elliptical galaxies have no particular axis of rotation.

Elliptical galaxy M87

Spiral Galaxies

Spiral galaxy M100

Spiral galaxies have three main components: a bulge, disk, and halo (see right). The bulge is a spherical structure found in the center of the galaxy. This feature mostly contains older stars. The disk is made up of dust, gas, and younger stars. The disk forms arm structures. Our Sun is located in an arm of our galaxy, the Milky Way. The halo of a galaxy is a loose, spherical structure located around the bulge and some of the disk. The halo contains old clusters of stars, known as globular clusters.

Spiral galaxies are classified into two groups, ordinary and barred. The ordinary group is designated by S or SA, and the barred group by SB. In normal spirals (as seen at above left) the arms originate directly from the nucleus, or bulge, where in the barred spirals (see right) there is a bar of material that runs through the nucleus that the arms emerge from. Both of these types are given a classification according to how tightly their arms are wound. The classifications are a, b, c, d ... with "a" having the tightest arms. In type "a", the arms are usually not well defined and form almost a circular pattern. Sometimes you will see the classification of a galaxy with two lower case letters. This means that the tightness of the spiral structure is halfway between those two letters.

Spiral galaxy NGC 1365


S0 Galaxies

S0 galaxies are an intermediate type of galaxy between E7 and a "true" spiral Sa. They differ from ellipticals because they have a bulge and a thin disk, but are different from Sa because they have no spiral structure. S0 galaxies are also known as Lenticular galaxies.
Irregular Galaxies

Irregular galaxies have no regular or symmetrical structure. They are divided into two groups, Irr I and IrrII. Irr I type galaxies have HII regions, which are regions of elemental hydrogen gas, and many Population I stars, which are young hot stars. Irr II galaxies simply seem to have large amounts of dust that block most of the light from the stars. All this dust makes is almost impossible to see distinct stars in the galaxy.

Large Magellanic Cloud

Astronomy

In the natural sciences an isolated system, as contrasted with a open system, is a physical system that does not interact with its surroundings. It obeys a number of conservation laws: its total energy and mass stay constant. They cannot enter or exit, but can only move around inside. An example is in the study of spacetime, where it is assumed that asymptotically flat spacetimes exist.
open system is one whose border is permeable to both energy and mass
Closed system: Can interchange energy and mechanical work with other outside systems but not matter.

Kepler's Laws of Planetary Motion are three mathematical laws that describe the motion of planets in the Solar System. German mathematician and astronomer Johannes Kepler (1571–1630) discovered them.

Kepler studied the observations of the legendarily precise Danish astronomer Tycho Brahe. Around 1605, Kepler found that Brahe's observations of the planets' positions followed three relatively simple mathematical laws.

Kepler's laws challenged Aristotelean and Ptolemaic astronomy and physics. His assertion that the Earth moved, his use of ellipses rather than epicycles, and his proof that the planets' speeds varied, changed astronomy and physics. Nevertheless, the physical explanation of the planets' behavior came almost a century later, when Isaac Newton was able to deduce Kepler's laws from Newton's own laws of motion and his law of universal gravitation, using classical Euclidean geometry. Other models of gravitation would give empirically false results.

Kepler's three laws are:

1. The orbit of every planet is an ellipse with the sun at one of the foci. An ellipse is characterized by its two focal points; see illustration. Thus, Kepler rejected the ancient Aristotelean, ptolemaic, and Copernican belief in circular motion.

2. A line joining a planet and the sun sweeps out equal areas during equal intervals of time as the planet travels along its orbit. This means that the planet travels faster while close to the sun and slows down when it is farther from the sun. With his law, Kepler rejected the Aristotelean astronomical theory that planets have uniform speed.

3. The squares of the orbital periods of planets are directly proportional to the cubes of the semi-major axes (the "half-length" of the ellipse) of their orbits. This means not only that larger orbits have longer periods, but also that the speed of a planet in a larger orbit is lower than in a smaller orbit.

GEOCENTRIC model of the universe is the theory that the Earth is at the center of the universe and the Sun and other objects go around it. Belief in this system was common in ancient Greece. It was embraced by both Aristotle and Ptolemy, and most Greek philosophers assumed that the Sun, Moon, stars, and naked eye planets circle the Earth. Similar ideas were held in ancient China.

Two common observations were believed to support the idea that the Earth is in the center of the Universe. The first is that the stars (including the Sun and planets) appear to revolve around the Earth each day, with the stars circling around the pole and those stars nearer the equator rising and setting each day and circling back to their rising point. The second is the common sense perception that the Earth is solid and stable; it is not moving but is at rest.

HELIOCENTRISM is the theory that the sun is at the center of the Solar System. The word came from the Greek (ήλιος Helios = sun and κέντρον kentron = center). Historically, heliocentrism is opposed to geocentrism and currently to modern geocentrism, which places the earth at the center. (The distinction between the Solar System and the Universe was not clear until modern times, but extremely important relative to the controversy over cosmology and religion.)

Although many early cosmologists such as Aristarchus speculated about the motion of the Earth around a stationary Sun, it was not until the 16th century that Copernicus presented a fully predictive mathematical model of a heliocentric system, which was later elaborated by Kepler and defended by Galileo, becoming the center of a major dispute.

rlp2008