Why Wine Glass Stem is so long?

Take 9 from 6, 10 from 9, 50 from 40, and leave 6.

How Come ??

Which is faster, Heat or Cold ? Explain.

Two guards were on duty outside a barracks. One faced up the road to watch for anyone approaching from the North. The other looked down the road to see if anyone approached from the South. Suddenly one of them said to the other, "Why are you smiling?"

How did he know his companion was smiling?

I have a clock(12-hour format) and both the needles of the clock overlap at 12:00.
After how much time, they will overlap again?

Can you think of a smallest +ve number such that if we shuffle the digits of the number, the new number becomes double the original number?

A man in a car saw a Golden Door, Silver Door and a Bronze Door. What door did he open first?

Who can jump higher than a Mountain?

I am something people love or hate. I change peoples appearances and thoughts. If a person takes care of them self I will go up even higher. To some people I will fool them. To others I am a mystery. Some people might want to try and hide me but I will show. No matter how hard people try I will Never go down. What am I?

A woman lives in a skyscraper thirty-six floors high and is served by several elevators which stop at each floor going up and down. Each morning she leaves her apartment and goes to one of the elevators. Whichever one she takes is three times more likely to be going up than down. Why?