Why Aeroplane windows are round?

We have four gears with below features=> Both Gear A and D has 60 teeth=> Gear B has 40 teeth=> Gear C has 20 teeth=> Every two minutes, Gear B makes 25 full turns.What is the relative speed of Gear A and Gear B?

A large container is kept in open under the rain. Every passing hour, the water collected inside the container becomes double what it was.

In ten hours, the container is filled completely. Can you calculate how long would it have taken to be filled in half?

Can you Find and name the hidden bird in the picture below ?

If I put in one canary per cage, I have one bird too many. If I put in two canaries per cage, I have one cage too many. How many cages and canaries do I have?

Can you find out what is missing?

1 3 5
2 4 ?

Hint: It's not six. Think out of the box.

Yesterday I fell from 30 feet high ladder but I don't get hurt. Why?

You can take four of the five letters out of this word, but the pronunciation never changes. What is the word?

What is the below Rebus indicate?

Count the Triangle in the figure given below: