GRAVITY AND BLACK HOLE
1. WHAT IS A BLACK HOLE?
Ans: If a small star is very dense, it may begin to shrink under the pull of its own gravity. As it shrinks, it becomes denser and denser and its gravity becomes more and more powerful-until it shrinks to a single tiny point of infinite density
called singularity. The gravitational pull of a Singularity is so immense that it pulls space into a “hole” like a funnel. This is the black hole, which sucks in everything that comes near it with its huge gravitational force- including light, which is
why it is a “black” hole.
2. WHAT IS GRAVITY?
Ans: Gravity is the mutual attraction between every single bit of matter in the universe. The more matter there is, and the closer it is, the stronger the attraction. A big, dense planet pulls much more than a small one, or one that is far away. The Sun is so big, it makes its pull felt over millions of kilometres of space. The Earth is smaller, but big enough to keep the Moon circling around it. The weight of an object is simply how hard gravity is pulling on it.
3. HOW STRONG IS A PLANET’S GRAVITY?
Ans: The more massive the planet that is the more matter it contains the more powerful its gravity. Astronauts on the Moon could jump up high in heavy spacesuits,because the Moon is much smaller than the Earth and its gravity is weaker.
4. HOW BIG IS A BLACK HOLE?
Ans: The singularity at the heart of a black hole is infinitely small. The size of the hole around it depends on how
much matter went into forming it. The black hole at the heart of our galaxy maybe about the size of the solar system.
5. WHAT ARE ORBITS?
Ans: In space, many objects such as planets and moons continually circle around larger objects.An orbit is the path they take. This is usually elliptical rather than perfectly circular in shape.
6. WHAT HAPPENS INSIDE A BLACK HOLE?
Ans: Nothing that goes into a black hole comes out, and there is a point of no return called the event horizon. If you went
beyond this you would be “spaghettified” – stretched long and thin until you were torn apart by the immense gravity.
7. HOW MANY BLACK HOLES ARE THERE?
Ans: No one really knows. Because they trap light, they are hard to see. But there may be as many as 100 million black holes in the Milky Way.
8. WHAT DID NEWTON DISCOVER?
Ans: The discoveries of Sir Isaac Newton (1642-1727) include the three fundamental laws of motion. He also discovered the force called gravity, which holds the Moon in orbit around the Earth, and the planets in orbit around the Sun.
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