What goes up but never comes down?

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

There are two candles. Both will only burn exactly for an hour. How will you use these two candles to measure forty-five minutes?

I get hot but I never sweat,
I cook food but I am not a chef,
I have a door but you can't enter me,
I have a light but I am not a lamp.
Who am I?

Can you decipher the following common phrase?

T M C
A U O
H S M
W T E

Mother's Name is Mrs. SIXTY TWO
Son's Name is FIFTY TWO
Daughter's Name is FORTY TWO
What is Name of Father?

You see a boat filled with people, yet there isn’t a single person on board. How is that possible?

Find out the missing number in the picture attached:

A mile-long train is moving at sixty miles an hour when it reaches a mile-long tunnel. How long does it take the entire train to pass through the tunnel?

On my way to St. Ives I saw a man with 7 wives. Each wife had 7 sacks. Each sack had 7 cats. Each cat had 7 kittens. Kittens, cats, sacks, wives. How many were going to St. Ives?