Isaac Newton, caricature
Isaac Newton. Caricature of the English scientist Isaac Newton (1643-1727), shown with a falling apple, representing his theories of gravity. It is said that Newton observed a falling apple and realised that the force that pulled it to Earth was the same as the force that kept the Moon and planets in their orbits. This led him to derive his equation of universal gravitation and his laws of motion, which formed the bedrock of science until the relativity theories of Einstein over 300 years later. As well as this, Newton designed a new type of telescope, studied light and devised calculus and the binomial theorem.
© Gary Brown/Science Photo Library
Ripe cashew nut
Ripe cashew nut. Image 2 of 2. Native to South America, the cashew (Anacardium occidentale) is now widely cultivated throughout the tropics. Cashew trees produce a fruit, known as an 'apple' (centre), and a nut (lower centre). The nut forms before the fruit swells and ripens, which takes two months. Once harvested, the fruit is often discarded in favour of the nut, although it can be used to make jellies, jams and juice. The nut must be removed from its shell with care, as the shell contains an allergen that can cause dermatitis. Cashew nuts are used in a variety of sweet and savoury recipes. Photographed in Grenada. See B790/237 for an unripe cashew nut.
© DAVID NUNUK/SCIENCE PHOTO LIBRARY
Fruit-powered clock. In this experiment each apple is a voltaic cell. The apples have been connected to make a battery. Copper (orange) and zinc (silver) electrodes have been inserted into the apples and connected to wires to produce electricity.
© Friedrich Saurer
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