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Showing posts from April, 2013

Is there any difference between antimatter and dark matter?

Anonymous asked :Is there any difference between antimatter and dark matter?

Answer:Anti matter is just like normal matter only the sign of certain properties is different.  The classic case would be the electron, which has as it's anti particle the anti-electron also known as the positron.  Electrons are negatively charged, and Positrons are positively charged.  Yet they are identical in every other way.    Then their are particles like neutrons and protons which are made of even smaller particles called quarks.  Quarks interact via the strong atomic force, and electromagnetism.  Anti Quarks have opposite charges to Quarks in those two forces.

Dark matter on the other hand only interacts by way of gravity and the weak atomic force.  Dark matter does not interact via either the strong atomic force or electromagnetism hence dark matter cannot be seen and is hard to detect.  It only interacts via the weak force which is what keeps neutrons and protons inside the nucleus of atoms toget…

XI Physics: Guess Paper / Impotant Questions 2013

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For Board of Secondary Education of Karachi



XII Physics: Guess Paper / Impotant Questions 2013

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For Board of Secondary Edacation of Karachi(BSEK)

The Physics Of Basketball

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Physics Of Basketball — Hang Time
Jumping is a major component of the physics of basketball. When a basketball player jumps in the air to make a shot he can appear to be suspended in mid-air during the high point of the jump. This is a consequence of projectile motion. When an object is thrown in the air it will spend a large percentage of time in the top part of the throw.
A basketball player can jump as much as 4 feet in the air (vertically). And the higher he jumps the greater the hang time (the total time he is airborne), and the greater the time he will appear suspended in mid-air during the high point of the jump. Typically, there is a horizontal and vertical component in the jump velocity at take-off. The magnitude of the vertical component of the velocity at take-off will determine the time the player spends airborne (since gravity acts in the vertical direction and will act on the player to bring him back down). Thus, the vertical component of velocity, after take-off, will …

Q.According to relativity Moving clock ticks slow..i have 2 much confusion to understand this statement as well time dilation

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Savera asked:
Q.According to relativity Moving clock ticks slow..i have 2 much confusion to understand this statement as well time dilation

Answer:Sure let us consider that You are "at rest", and there's a rocket going past you, and a person on the rocket is holding a clock, a flashlight, and a meter stick oriented in the direction of travel. You also hold a clock, a flashlight, and a meter stick.

You see a one-meter-long stick, and a clock ticking at one tick per second, and you see the light traveling at the speed of light.

The person on the rocket also sees his stick as one meter long, the clock ticking at one tick per second, and the light traveling away at the speed of light.

But, when you look at the rocket, you see a meter stick that is shorter than a meter, and a clock that is ticking slower than one tick per second, but the light from the flashlight is still traveling at the speed of light. 

It turns out that the person on the rocket sees the same thing w…

Quranic Explanation of Wormholes

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Look up to the night sky and select a star as a destination. Can any human reach this star by just walking few steps? General relativity explained a mechanism to contract huge distances into few meters. Albert Einstein called this mechanism ‘bridges’ in space-time.

Today, scientists call them wormholes.
A wormhole acts as a shortcut connecting two distant regions in the universe.
God gave this method of transportation to his angels throughout the universe. The Quran calls them ‘Ma'arej’ (معارج) and describes how angels use them for long distance travel. Today Moslems know that these ‘Ma'arej’ is what scientists call wormholes.
Physicists know how a wormhole works but have never actually used one. Do you remember how a frictionless roller coaster works? That is, you start high and slow then you go down and fast but when you come back up again to your previous height you return to your previous slow speed? Well, the wormhole is the most efficient roller coaster yo…

An Introduction to Wormholes

Quranic Explanation of Pulsars & Black Holes

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Neutron stars are remnants of exploded stars. As more matter falls into a neutron star its mass increases; and as its mass increases its gravity increases. A point will be reached where gravity would have grown so much that not even light could escape, thus a black hole forms. Most neutron stars discovered today are in the form of radio pulsars. They are called radio pulsars because they emit radio waves. We can simply connect a radio telescope to a loud speaker and hear a pulsar. Pulsars sound like someone persistently knocking. Click here and listen to a slow knocking pulsar. Click here and listen to a fast knocking pulsar. So in short, we can hear a pulsar knock; and if matter continues to fall into this pulsar a black hole will eventually form. Moslems say that this is what Allah says. The Quran describes a star by "The one who knocks" and says that it is "The one who makes a hole". [Quran 86.1-3] And the heaven and the "Knocker…

Quranic Explanation of Big Bang and Big Crunch

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After the Big Bang the universe was primarily Hydrogen, Helium and a tiny bit of Lithium. However when a gas is too hot it becomes ionized (loses the electrons) and becomes opaque (like today's smoke). In the beginning the universe was opaque to visible light (non-transparent). After 380,000 years the universe cooled enough and it became transparent to visible light. For other wavelengths it was opaque for a billion years. So "Let there be light" turned out to be false. However the Quran correctly said that at the beginning it was SMOKE, that is, a hot non-transparent gas:
[Quran 41.11] Then He directed himself to the Heaven when it was SMOKE, and then said to it and to Earth: "Come willingly or by force" they said "We do come willingly" How could an illiterate man who lived 1400 years ago have known that it was just smoke after the Big Bang? The universe was created in a Big Bang 13.7 billion years ago, is still …

Quranic Explanation of Kepler's Law

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For centuries it was believed that Earth is fixed and the sun, moon and planets revolve around it. However 1400 years ago the Quran said that not only the sun and moon but even Earth moves in a designated path: [Quran 39.5] [Allah] Created the heavens and the Earth in truth. He overlaps the night over the day and overlaps the day over the night, and enslaved the sun and the moon, ALL MOVE (Kullon Yajree كل يجري) to a prerecorded destiny. Is He not the Exalted, the Forgiver? Here the Quran is referring to ALL MOVING: not only the sun and moon but also Earth. In Arabic grammar there is difference between the singular (one), binary (two) and plural (three or more). The reference to binary is "Kulahuma Yajreean كلاهما يجريان" however the Quran said "Kullon yajree كل يجري" referring to the plural (three or more). Since the sun and moon are just two but the Quran refers to three or more then accord…

Quranic Explanation of Singularity

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All stars will eventually die. They will either directly collapse on themselves and become black holes, or their remnants will merge with other stars that will eventually become black holes, or if external mass falls into those remnants they will blow up and leave black holes... So black holes are the destiny of most stars. Actually our solar system formed out of debris of a star 100 times more massive than our sun that exploded and became a black hole.

At the center of black holes (collapsed stars) lies a location called the Singularity. An observer far away from a black hole sees the events near a back hole in slow motion. If he shines a beam of light into this black hole he will have to wait forever but still this beam of light will never reach the singularity. The singularity is a location in the future of stars where gravity goes so mad that space and time become indistinguishable. From general relativity we know that this is a location where the structure of spacetime becomes s…