What is the centre of gravity?

Take number 1000 and then add 20 to it.
Now add 1000 one more time.
Now add 30.
Now add 1000 one more time.
Now add 40.
Now add 1000 one more time.
Now add 10.

What is the total?

I have branches, but no fruit, trunk or leaves. What am I?

If it took eight men ten hours to build a wall, how long would it take four men to build it?

What has many teeth, but cannot bite?

Can you make a six-letter word using the letters N, A and B ?

John killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?

It's a protector.
It sits on a bridge.
One individual can see directly through it, while others wonder what it hides.

What is it?

My friends called me Iron59 because my parents are a chemist and a mathematician. What is my real name?

For this puzzle, you might have to find logic in something illogical. But hey, it's fun and a healthy little break from your strenuous puzzle-solving sessions.

Can you decipher the meaning in the following cluster of letters?

ITIT,NCENTCENT