Question

please help with this physics question & explain please !

Answer 1

how fast should you launch an object horizontally so that it goes around earth (doesn't fall down to earth)

every 8 km comes with 5km closer to earth
- they are the distance that the earth curves

Answer 2

The principle is pretty much the same of letting satellites orbit around the earth. The body are constantly falling down, but they never hit the Earth.
You might want to take a look at this (you'll find your answer here):

http://science.howstuffworks.com/satellite2.htm