What goes up but never comes down?

I come in different shapes and sizes.
Parts of me are curved, other parts are straight.
You can put me anywhere you like,
but there is only one right place for me.
What am I?

What is black when you buy it, red when you use it, and gray when you throw it away?

How many cubic feet of dirt are in a hole of one foot deep, three feet long, and two feet wide?

What does the following represent?

N N N N N N N

A A A A A A A

C C C C C C C

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

A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?

A newspaper is supposed to have 60 pages.Pages 14 and 21 are missing from the newspaper.

Can you tell me , Which other pages won't be there as well ?

Why do Chinese men eat more rice than Japanese men do ?

A Car is crossing a bridge 2 miles long. The bridge can only hold 10000 lbs, which is the exact weight of the car. The Car makes it half way across the bridge and stops. A bird lands on the car. Does the bridge collapse? Explain.