There is one thing that goes round the house and also inside the house but never even share a brief touch. What is it?

Three cars are driving on a track that forms a perfect circle and is wide enough that multiple cars can pass anytime. The car that is leading in the race right now is driving at 55 MPH and the car that is trailing at the last is going at 45 MPH. The car that is in the middle is somewhere between these two speeds.
Right now, you can assume that there is a distance of x miles between the leading car and the middle car and x miles between the middle car and the last car and also, x is not equal to 0 or 1.
The cars maintain their speed till the leading car catches up with the last car and then every car stops. In this scenario, do you think of any point when the distance between any two pairs will again be x miles i.e. the pairs will be x distance apart at the same time ?

How old is your son? asked a man to his neighbour. My son is five times as old as my daughter and my wife is five times as old as my son. I am twice as old as my wife whereas my grandmother, who is celebrating her eighty-first birthday is as old as all of us put together.

How old is the man's son ?

What are the next two letters in the following series and why?
W A T N T L I T F S _ _

*Hint: Check Puzzle Title

Only one colour, but not one size,
Stuck at the bottom, yet easily flies.
Present in sun, but not in rain,
Doing no harm, and feeling no pain.
What is it?

If an earthquake is 1 point higher on the Richter Scale than another earthquake which is actually 10 times stronger, how much stronger would an earthquake be if it was just half a point higher on the Richter scale?

Before Mount Everest was discovered, what was the highest mountain in the world?

Can you name four days which start with the letter 'T'?

Can you write down eight eights so that they add up to one thousand?

Can you replace the question mark with the correct number?