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Final revision 3 prep.

المراجعة النهائية

إهداء إلى أبنائى و بناتى طلاب الصف الثالث الاعدادى

أعلم حرصكم على حل أسئلة كتاب الوزارة بالمراجعة النهائية

لذا جمعت لكم كل هذه الاسئلة و أكثر

أسألكم من صالح دعائكم

التحميل من هنا

المراجعة النهائية

Science

الصف الثانى الاعدادى

حمل من هنا

Final revision for 1 prep. 1st term

التحميل من هنا

Final revision 4 primary

المراجعة النهائية للصف الرابع الابتدائى ترم أول

http://www.mediafire.com/?eotf1uff9bf9hlu

Physics for 1st Secondary

THE STRONGEST & THE FASTEST

PHYSICS REVISION

FOR 1 SECONDARY

أقوى و أسرع مراجعة لمنهج الفيزياء الصف الاول الثانوى

حمل من هنا

You are great

Keep away from people who try to belittle your ambitions. Small people always do that, but the really great ones make you feel that you too, can become great. – “Mark Twain”

Mitosis phases

meiosis phases


What happened to Pluto?

We all grew up learning in school that we have 9 planets in our solar system. And the most popular and mysterious of them is Pluto. No one loves the planet Pluto more than kids! In fact, after Pluto was discovered in 1930, the name was suggested by an 11 year old schoolgirl living in Oxford England who was very interested in classical mythology and astronomy. No, Pluto is not named after the lovable friend of Mickey Mouse, Pluto is the Roman god of the underworld. In fact, Pluto the Disney dog was also created in 1930 and named after the planet Pluto!

Here are some more cool facts. Did you know that Pluto is smaller than our moon? And because it’s so small and far away, even our strongest telescopes can’t get a good picture of it. So you wont see it when you’re star gazing, in fact no one really knows what it looks like! But if all goes well, when the New Horizons spacecraft flies by Pluto in 2015, we will finally have up-close pictures of the most popular former planet. Have you memorized the planets and their order from the sun? If not, here’s an easy way to remember: My (Mercury) Very (Venus) Educated (Earth) Mother (Mars) Just (Jupiter) Served (Saturn) Us (Uranus) Nine (Neptune) Pizzas (Pluto). This is called a mnemonic device (pronounced ni-mon-ik) which means it helps your memory. We have solar system model kitsthat teach this and science activity books as well!

In 2005, astronomers discovered what they thought was the 10th planet, and temporarily named it after the TV inspired character – Xena (pronounced – Zee-nuh) the Princess Warrior. In September of 2006 they officially gave Xena the name Eris from the Greek goddess of discord and strife. Because Eris is about 5% bigger than Pluto,astronomers decided it was obvious that either they are both planets, or they are both something else. After Eris was discovered the IAU (International Astronomical Union) decided to wait to make a decision on the status of Eris until it was decided what a “planet” actually was.

So what happened to Pluto? Why is it no longer considered a planet? Believe it or not, this debate has been going on for a long time. In August of 2006, 424 astronomers finally got together to vote on the definition of “planet.” The definition they came up with would no longer consider Pluto a planet, but rather a dwarf planet. The astronomers decided on 3 criteria that make up a “planet”:

1) The object must be in orbit around the Sun. Well, Pluto does that!

2) Size was the second factor. Remember that Pluto is actually smaller than our moon. But who is to say exactly how big a planet needs to be? Well, the astronomers decided that to be a “planet”, the object has to be big enough that gravity squeezes it into a round shape (a sphere) like an orange or a basketball. An asteroid will have an odd shape, often like a potato, because it’s just not that big. When a body is large enough to be squeezed into a round shape, it’s called hydrostatic equilibrium.

3) The third thing they decided on also has to do with size. They agreed that an object must be big enough that it’s gravity removes other objects that occupy the same orbit. That means that as Pluto follows a certain path around the Sun, no asteroids or other objects can occupy the same path around the Sun. But Pluto does not meet this criterion. Pluto is in a section of our solar system called the Kuiper belt which is made up of ice asteroids.

So according to the IAU, Pluto meets only 2 of the 3 criteria and therefore is considered a dwarf planet, along with Xena (now Eris).

Also, Pluto has an orbit that is eccentric (oval-shaped), yet the other 8 planets have circular orbits. This is something that has bothered astronomers for a long time. It means that Pluto’s orbit brings it closer to the sun twice during its 248 year revolution around the sun. If you want to visualize this get a pencil or Crayon and a piece of paper and first draw the sun, make it about the size of a penny. Then draw a large circle around it. Try to make it as close to a perfect circle as you can! This will be Neptune’s orbit around the sun. Remember, Neptune is the 8th planet from the Sun. Now draw an oval that overlaps Neptune’s orbit so that two sides of the oval are inside the circle and two sides are outside the circle. This is Pluto’s orbit. As you can see Pluto’s orbit comes closer to the sun than Neptune’s. It’s not one of the 3 planet criteria, but it’s an oddity.

Many people were very happy that Pluto was no longer considered a planet, but other people were so upset they started petitions and websites to try and convince the IAU to reinstate Pluto as a planet. There were even bumper stickers made up that said “Honk if Pluto is still a planet!”

So what do you think? Are you convinced that Pluto is a dwarf planet based on what the astronomers decided, or do you think Pluto should be a planet just like the other 8? This debate will likely go on for a long time!

In physics or physical science, acceleration (symbol: a) is defined as the rate of change (or derivative with respect to time) of velocity.

To accelerate an object is to change its velocity, which is accomplished by altering either its speed or direction (like in case of uniform circular motion) in relation to time.

In this strict mathematical sense, acceleration can have positive and negative vals (deceleration).

Any time that the sign (+ or -) of the acceleration is the same as the sign of the velocity, the object will speed up.

If the signs are opposite, the object will slow down.

Acceleration is a vector defined by properties of magnitude (size or measurability) and direction.

When either velocity or direction are changed, there is acceleration (or deceleration).

One of the toughest things to learn is how to enjoy learning. That sounds a little ridiculous but it’s very true. Children begin to become interested in learning at a very young age. By the time most people are only 4 years old they are discovering more and more about the things they are interested in.  So how do we encourage this behavior? How do we help our children want to learn and develop a desire for knowledge? They only way to help children stay interested in learning is to make learning something they want to do. As with most successful child-learning-support techniques it involves YOU the parent/teacher. It’s really quite simple! Children learn best by doing things, whatever they are. By learning from your example and from hands-on experience we get a real example of how things work. Setting the precedent that you want to learn is the first step. When you are picking an activity to do with your children try to let them pick an activity. Letting them pick increases your chances of keeping them focused through the whole task and shows them that they can get excited about things they’re learning and that you can learn even from fun things. Have them choose ahead of time so you can prepare, or have several activities prepared and let them choose from those. Even if they don’t like all of the choices at least they get to choose, a symptom of which they will subtly learn responsibility for their own choices.  If your kids are into sports, teach them about Physics. Sports where you hit a ball like Baseball, Cricket, Tennis, and Golf deal with many Physical concepts. You could discuss how the speed and spin of the ball effects the game, or how the angle you hit the ball, or the bounce as the ball hits the turf effect the game. Professional baseball players have many different formulas for getting a Triple Play! Formulas in themselves are scientific. All sports can be a fantastic lesson in physiology! Studying how our bodies work is vital to athletes and trainers alike. Everything from studying how certain muscles move to better understand how to train a certain movement like a throw or a jump, to how your body uses food for fuel and how your pulmonary system works to keep you oxygenated during vigorous activity, it’s all science! Just going for a walk in your neighborhood can become a lesson in science. Playground equipment can help teach physical concepts. You can talk about the fulcrum in a see saw, or how swings work by shifting your weight. The slide is a lesson in inertia and friction and “monkey bars” are full of opportunities for studying gravity and the wonders of muscles in our body. While you are at the park take some time to notice any wildlife around you. Birds and other animals can become a biology lesson. Ask your kids to attempt to identify all the animals you see. Maybe you could have them make note of how many different animals they noticed and any interesting behaviors they observed in a field journal. You can also do this with flowers and trees. Letting your kids help you cook dinner is the perfect time to discuss science. Talk about the equipment you are using, how the temperature affects your recipe, how the ingredients interact. Explain how water boils, how evaporation occurs to thicken your sauce or how baking soda and yeast help to make bread rise. There are also many safety issues that can be discussed in the kitchen, and many of those directly relate to working in a laboratory when your kids are older. Safety when dealing with heat, boiling liquids, and cross contamination are all things they can learn about at home with you and apply in class. Science is all around us. Cooking is chemistry, carpentry is engineering, gardening is botany with a touch of geology. Even the arts, especially music, involve science and math. No violin or electric guitar could make a sound without physics. So many everyday things can be approached from a scientific stance. You can take any subject that your children are interested in and show them it can be fun to learn!