Answer:
Space junk is travelling so fast that a collision with an astronaut or a spacecraft could be disastrous.
Explanation:
Space junk orbits the Earth at speeds of about 28 000 km/h.
That's so fast that even an orbiting fleck of paint has enough kinetic energy to cause impact craters on the surface of a spacecraft. They are even more dangerous to an astronaut on a space walk.
Much of the space debris is larger and more dangerous than a fleck of paint.
One rough estimate of the amount of space debris is
<em> </em><u>Size</u><em> </em> <u>Number of objects</u>
< 1 cm 200 000 000
1 cm to 10 cm 700 000
> 10 cm 30 000
Satellites, etc. 18 000
The chances of collision are small, but any collision can be disastrous.
Answer:
No 1 is fission
while no 2 is fusion
Fission is splitting on nucleus while fusion is forming heavier nucleus with nuclei
The metric system is used because it is based on the number 10. Ten is easy to use for mathematical operations and conversions.
It is also easy to use for scientific notation when you are referring to powers of ten. There are extremely large and extremely small numbers in science. Thus, scientific notation allows for accurate abbreviated ways to symbolize these numbers. For instance, if I were to say 1,000, in scientific notation it would be 1 x 10 ^3. If I was to say 1,000,000, I would scientifically write 1 x 10 ^6.