Fuel is any material that is capable of releasing energy when its chemical or physical structure is changed or transformed. Fuel releases its energy either through chemical means, such as burning, or nuclear means, such as nuclear fission or nuclear fusion. An important property of a useful fuel is that its energy can be stored to be released only when required, and that the release is controlled in such a way that the energy can be harnessed to produce work.
All carbon-based life forms—from microorganisms to animals and humans—depend on and use fuels as their source of energy. Their cells engage in an enzyme-mediated chemical process called metabolism that converts energy from food or solar power into a form that can be used to sustain life. Additionally, humans employ a variety of techniques to convert one form of energy into another, producing usable power for purposes that go far beyond the energy needs of a human body. The application of energy released from fuels ranges from heat to cooking and from powering weapons to propulsion and production of electricity.
Fuel is any material that is capable of releasing energy when its chemical or physical structure is changed or transformed. Fuel releases its energy either through chemical means, such as burning, or nuclear means, such as nuclear fission or nuclear fusion. An important property of a useful fuel is that its energy can be stored to be released only when required, and that the release is controlled in such a way that the energy can be harnessed to produce work.
All carbon-based life forms—from microorganisms to animals and humans—depend on and use fuels as their source of energy. Their cells engage in an enzyme-mediated chemical process called metabolism that converts energy from food or solar power into a form that can be used to sustain life. Additionally, humans employ a variety of techniques to convert one form of energy into another, producing usable power for purposes that go far beyond the energy needs of a human body. The application of energy released from fuels ranges from heat to cooking and from powering weapons to propulsion and production of electricity.Fuel is any material that is capable of releasing energy when its chemical or physical structure is changed or transformed. Fuel releases its energy either through chemical means, such as burning, or nuclear means, such as nuclear fission or nuclear fusion. An important property of a useful fuel is that its energy can be stored to be released only when required, and that the release is controlled in such a way that the energy can be harnessed to produce work.
All carbon-based life forms—from microorganisms to animals and humans—depend on and use fuels as their source of energy. Their cells engage in an enzyme-mediated chemical process called metabolism that converts energy from food or solar power into a form that can be used to sustain life. Additionally, humans employ a variety of techniques to convert one form of energy into another, producing usable power for purposes that go far beyond the energy needs of a human body. The application of energy released from fuels ranges from heat to cooking and from powering weapons to propulsion and production of electricity.

The Orca or Killer Whale is not a whale, but the largest species of the oceanic dolphin family. They are sometimes referred to as blackfish, a group including pilot whales, pygmy and false killer whales, and melon-headed whales. It is the second-most widely distributed mammal on Earth and is found in all the world's oceans, from the frigid Arctic regions to warm, tropical seas. It is also a versatile predator, eating fish, sea turtles, seabirds, pinnipeds, elasmobranchs, sirenians and even other cetaceans. This puts the orca at the pinnacle of the marine food chain. Orcas have been known to attack baleen whales, in particular gray and Blue whales.
Orcas are magnificent marine mammals, with a fearsome reputation that goes as far back as Pliny the Elder's description of the species. The name "killer whale" reflects the animal's habit of attacking whales, and does not mean that orcas are a threat to humans. Aside from a boy who was charged while swimming in a bay in Alaska, there have been no confirmed attacks on humans in the wild. There have, however, been isolated reports of captive orcas attacking their handlers at marine theme parks.