Facts At Your Fingertips: The living world Earth is the only place in the universe where life is known to exist. Millions of different kinds of life-form are found all over the planet. Some, such as bacteria, are too small to see with the naked eye, while others, such as trees, may be more than … Read more
Facts At Your Fingertips: Energy and forces – Computers A computer is a machine that can be programmed to perform a huge range of tasks. Computers work using simple electronic circuits, called transistors, which can only be turned on or off. Millions of transistors can be combined to form microprocessors, which process instructions and tell … Read more
Facts At Your Fingertips: Energy and forces – Complex machines Simple machines can be combined to make complex machines. A pair of scissors is a complex machine that combines two types of simple machine—the blades as wedges and the handles as levers. The Space Shuttle was probably the most complex machine ever built, with more … Read more
Facts At Your Fingertips: Energy and forces – Simple machines We use simple machines to help us do our work more easily. There are six kinds of simple machine. They change the direction or size of a force, allowing us to use less effort when moving, separating, or keeping heavy objects in place. Inclined planes … Read more
Facts At Your Fingertips: Energy and forces – Forces and movement Whenever an object changes speed or direction, this happens because a force is acting on it. More than 300 years ago, the English scientist Isaac Newton worked out three laws of motion that explain how forces affect movement. First law of motion The first … Read more
Facts At Your Fingertips: Energy and forces – Forces Forces are pushes and pulls that change an object’s shape or movement. Every time an object speeds up, slows down, or changes direction, this happens because a force is acting on it. Forces such as gravity can act over huge distances, keeping the planets in orbit … Read more
Facts At Your Fingertips: Energy and forces – Sound Sounds are vibrations that we hear with our ears. The vibrations travel through substances such as air or water in the form of sound waves. When the waves reach our ears, they make our eardrums vibrate. The size and shape of the waves determine the kind … Read more
Facts At Your Fingertips: Energy and forces – Heat The atoms and molecules that make up matter are always on the move. The more energy they have, the faster they move. We feel this energy as heat. Heat will always move from a warmer area to a colder one until both areas are the same … Read more
Facts At Your Fingertips: Energy and forces – Radioactivity In some atoms, the nucleus changes over time, releasing particles and energy, known as radiation. This process is called radioactive decay. We encounter low-level radiation all the time—in the soil, in the air, and in the food we eat. Types of radioactivity There are three types … Read more
Facts At Your Fingertips: Energy and forces – Using light We need light to see the world and to find our way around it. In the earliest days of humanity, we just used the natural light produced by the Sun and went to bed when it got dark. Today, we can also use artificial lights … Read more
