What has one letter and starts with an E?

When my father was 31 I was 8. Now he is twice as old as me. How old am I?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

I don't get anymore wetter, no matter how much rain falls on me.

I have a head like a cat and feet like a cat, but I am not a cat. What am I?

The Puzzle: A girl, a boy, and a dog start walking down a road.

They start at the same time, from the same point, in the same direction.

The boy walks at 5 km/h, the girl at 6 km/h.

The dog runs from boy to girl and back again with a constant speed of 10 km/h. The dog does not slow down on the turn.
How far does the dog travel in 1 hour?

What has to be broken before you can use it?

I am a white box having no key or lid.
Yet there is a golden treasure inside it.

What Am I?

I have four wings but can't fly.
I express no emotions.
I am found on the exact spot every time you look.
I keep toiling away with a little sound.

Do you know what am I?

If,

A = 1

B = 2

C = 3

...

...

Z = 26.

Based on above rule, you need to find an eleven letter word whose letter sum is equal to 52.