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4 天前 · Kinetic energy is a property of a moving object or particle and depends not only on its motion but also on its mass. The kind of motion may be translation (or motion along a path from one place to another), rotation about an axis, vibration, or any combination of motions. Translational kinetic energy of a body is equal to one-half the product ...
2024年4月15日 · Electromagnetic radiation is, classically speaking, a wave of electric and magnetic fields propagating at the speed of light c through empty space. In this wave the electric and magnetic fields change their magnitude and direction each second. This rate of change is the frequency ν measured in cycles per second—namely, in hertz.
2024年5月3日 · The lepidopteran life cycle has four stages: egg, larva ( caterpillar ), pupa (chrysalis), and adult (imago). The larvae and adults of most butterflies feed on plants, often only specific parts of specific types of plants. Mourning cloak butterfly (Nymphalis antiopa). Learn about the monarch butterfly, including its annual migration to Mexico.
France is among the globe’s oldest nations, the product of an alliance of duchies and principalities under a single ruler in the Middle Ages. Today, as in that era, central authority is vested in the state, even though a measure of autonomy has been granted to the country’s régions in recent decades. The French people look to the state as ...
2024年5月5日 · Hydrogen, a colorless, odorless, tasteless, flammable gaseous substance that is the simplest member of the family of chemical elements. The earliest known chemical property of hydrogen is that it burns with oxygen to form water; indeed, the name hydrogen is derived from Greek words meaning ‘maker of water.’.
1 天前 · It is also the world’s highest, driest, windiest, coldest, and iciest continent. Antarctica is about 5.5 million square miles (14.2 million square km) in size, and thick ice covers about 98 percent of the land. The continent is divided into East Antarctica (which is largely composed of a high ice-covered plateau) and West Antarctica (which is ...
2 天前 · The Renaissance was a period in European civilization that immediately followed the Middle Ages and reached its height in the 15th century. It is conventionally held to have been characterized by a surge of interest in Classical scholarship and values. The Renaissance also witnessed the discovery and exploration of new continents and numerous important inventions.
