Outer Space

Why do stars have different colors?

How things work

How does a combination lock work? Why is it considered more secure than the cylinder lock?

World

Why was it predicted that the world ends on December 21, 2012?

World

Which countries have been under foreign rule for more than a century?

How things work

How do sound waves travel through air? Why do they move faster in water than in air?

World

What are Polarized sunglasses? How do they work?

Living Creatures

Is Hummingbird the Smallest Bird? How Small is It?

Science and Technology

Why are dark things warmer than light colored or simply white things?

Science and Technology

Why a multistage rocket is needed to get a spacecraft off the Earth and into the space?

Outer Space

How will the Universe end? Or will it go on expanding forever?

How things work

Why an automobile's windscreen glass shatters into rounded pieces when it breaks?

World

Why are the ten basic numerals called Arabic numerals even though their script is not Arabic?

Science and Technology

Why is a problem in a computer program called a bug?

Science and Technology

How millions of transistors switch on and off to register the digital 1 and 0 in the microchip?

Science and Technology

Why the capacity of air conditioners is expressed in tons instead of horsepowers?