Shears, Scissors

Scissors are a tool used for cutting thin material which requires little force. They are used for cutting, for example, paper, cardboard, metal foil, thin plastic, food, cloth, rope and wire. They are also used for cutting hair and nails. more...

Unlike a knife, scissors have two pivoted (or hinged ) blades. Most types of scissors are not particularly sharp; it is primarily the shearing between the two blades which cuts. Children's scissors are even less sharp, and are often protected with plastic.

Although often used interchangeably with "scissors", the term shears are reserved by those in the industry for scissors longer than 15 cm.

Although commonly ascribed to Leonardo da Vinci, scissors were likely invented in 1500 BC in ancient Egypt. These were likely shears with the joint at the far end. Modern cross-bladed scissors were invented by Romans around AD 100.

Mechanically, scissors are a first-class, double-lever with the pivot/hinge acting as the fulcrum. For cutting thick or heavy material, the mechanical advantage of a lever can be exploited by placing the material to be cut as close to the fulcrum as possible. For example, if the applied force (i.e. the hand) is twice as far away from the fulcrum as the cutting location (e.g. piece of paper), the force at the cutting location is twice that of the applied force at the handles. Specialized scissors, like bolt cutters exploit leverage by having a long handle but placing the material to be cut close to the fulcrum.

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