I never stop running even when I standstill. If I am formed by joining two identical bodies together, can you guess who I am?

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?

A seven-year-old kid challenged his classmates that he can make the number one disappear by adding something to it.

How can he do that?

Your last good ping-pong ball fell into a narrow metal pipe embedded one foot deep in concrete.
How can you get it out undamaged, if all the tools you have are your tennis paddle, shoe laces, and plastic water bottle, which does not fit into the pipe?

Why is it very easy to weigh a fish?

If an electric train is travelling south, then which way is the smoke going?

I have branches, but no fruit, trunk or leaves. What am I?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

What runs around the whole yard without moving?

What is the riddle which can be asked all day with a different correct answer each time.