multiple choice questions -...

High School Teacher Program 2008 Multiple choice questions

Multiple choice questions Recommended for12-18 yrs olds

Summary These multiple choice questions can be the start of a lesson to catch the attention of the sThey can be the start of a discussion or let students fantasize about our Universe…

tudents.

Concepts Black hole, force, age of the Universe, dark matter, accelerators, particle physics, …

Link to the curriculum This lesson can cover the following topics:

• Matter • Particle physics • Cosmology

Multiple choice questions

1. What is a Black Hole?

o never heard about it o a large hole in the earth where you cannot get out any more o the end product of a star o a hole in your teeth

2. Which force holds the universe together? o don´t know o gravity o Strong Force o electromagnetic force

3. How big is the universe? o we don´t know yet o it is infinite o it is finite but I don´t know how big o its size is 10 m

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4. What is Dark Matter? o brown dwarfs o matter in the universe we don´t know about o Black Holes o antimatter

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5. How old is our body?

o we don´t know o 13,7 billion years o as long as the earth exists o our age

6. What is an accelerator? o some device that makes you run faster o something that belongs to science fiction stories but does not really exist o a machine that accelerates tiny particles to reach almost light velocity o some device needed in hospitals

7. Where can you use particle physics? o nowhere-it only exists in the mind of physicists o to do scientific research o in medicine o in industry

8. Up to which velocity can you accelerate particles? o more than light velocity o exactly light velocity o less than light velocity but pretty near o much less- about the velocity of an aircraft perhaps

Multiple choice questions - answers 1) What is a Black Hole? o the end product of a star

When a star dies it gives away in an outburst much mass (Supernova). If the remaining mass is more than about 8 times the mass of our sun the gravity is so big that the mass will collapse and attract everything within a certain distance – even light. Because it absorbs light it seems to be black. It can be compared with a “vacuum cleaner” in the universe.

2) Which force holds the universe together? o gravity

There are 4 forces: Strong Force holds the nucleus of an atom together Weak Force is responsible e.g. for the radioactive decay Electromagnetic force holds an atom together Gravity holds the earth, sun, galaxies etc. together

3) How big is the (visible ) universe? o its size is 10 m 26

It is finite- the distance that light could cover since the beginning in the Big Bang (as light is the fastest object).

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The universe is expanding. Light covers a distance of about 10 16 m in 1 year. The universe is about 13,7 10 years old.

The size of the universe must be the distance light could cover since the Big Bang. Thus the size is the product of these 2 parameters: about 10 m.

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4) What is Dark Matter? o matter in the universe we don´t know about

As the stars orbiting around the centre of a galaxy are moving too fast in relation to the attraction by the gravity of the visible mass in a galaxy there has to be invisible matter in between the orbiting stars in order to create such a big gravitational field. But until now nobody knows what it consists of. The visible matter in the whole universe is only about 4% of the whole energy, 22% is dark matter, the rest unknown energy.

5) How old is our body? o 13,7 billion years

All elements and atoms our body consists of have been created in stars in a process called nuclear fusion. At the end of it´s life the dying star emits most of this material into space where after some time new stars can be created out of this material – a kind of cosmic ”recycling”. Before that there had to be protons and electrons and before that quarks of which protons exist…..So all these particles we consist of date from the beginning of the world and this has been about 14 billion years before.

6) What is an accelerator? o a machine that accelerates tiny particles to reach almost light velocity o some device needed in hospitals

In reality tiny particles are accelerated by strong gravitational or magnetic fields. In order to detect and identify them huge machines are built. When they bump into each other at high velocities much energy is created and many things may happen – such as decay, creating new particles,... You can use that in hospitals e.g. the PET. Cancer can be detected and cured.

7) Where can you use particle physics? o to do scientific research o in medicine o in industry

First physicists do some scientific research, then all their knowledge can be used by hospitals in order to detect and cure e.g. cancer. But also the new found technology is used by the industry in order to produce smaller and smaller devices. By the way: did you know that the World Wide Web was also invented by particle physicists in CERN – helping to communicate faster than until then.

8) Up to which velocity can you accelerate some material? o less than light velocity but pretty near

Einstein showed in his Special Relativity Theory that mass increases when it gets faster. You cannot see this in everyday life but only when something is already near the

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speed of light. As the mass is growing with speed any further acceleration needs more force/energy…At the speed of light the mass would be infinite and so you would need infinite energy which is not possible. Only objects without mass like light particles (photons) can reach the speed of light. So this is the highest possible velocity that is possible. And even our fastest rockets can never reach this speed. Only small particles like e.g. electrons or protons can be accelerated to almost the speed of light which needs much energy!

Nice experiment… What has a balloon to do with the expansion of the universe? You must take a balloon with many small points of about the same size and in about the same distance from each other. When you blow it up it is a model for the expanding universe. The longer you blow the bigger it gets. When you observe the growing balloon you will see that the points symbolizing the galaxies not only increase their distance from the centre of the balloon (expansion since the “Big Bang”) but also the distance between each other. So it is a model also for the redshift that gives evidence of the fact that almost everything is expanding- in any direction. The difficult thing to understand is that in “blowing up the balloon” time and space are created! Or if you follow the track back to the origin of the universe: time and space vanish.

©2008 HST-2008

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