Why do people go to bed?

Two-person want to cross a river. Only one boat is present on the riverside that can carry only one person at a time.

However, they still manage to cross the river. How is it possible?

If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?

Which alphabet letter is a question?

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

A man who was outside in the rain without an umbrella or hat didn’t get a single hair on his head wet. Why?

How is the moon similar to a dollar?

Can you solve the below algebraic mathematical equation?

(J+O+I+N+T)3 = JOINT

I am quite hot but become too cold if you remove the first two letters. What am I?

I am five letter word that is under you.
If you remove my 1st letter, then I am over you.
If you remove my 1st and 2nd letters then I am all around you.

Who am I?