Fulcrum

(noun.) the pivot about which a lever turns.

丹尼尔编辑

• The fulcrum is at the wheel, the force is at the handles, the weight is on the wheelbarrow. 伯莎M.克拉克. 科学通论.
• Move the 4-pound weight so that it is very near the fulcrum, say but 6 inches from it; then the spring balance registers a force only one fourth as great as the weight which it suspends. 伯莎M.克拉克. 科学通论.
• The nutcracker (Fig. 101) is an illustration of a double lever of the wheelbarrow kind; the nearer the nut is to the fulcrum, the easier the cracking. 伯莎M.克拉克. 科学通论.
• If the load is one fourth as far from the fulcrum as the man's hands, he will need to lift with a force only one fourth as great as that of the load. 伯莎M.克拉克. 科学通论.
• For example, the fulcrum is sometimes at one end, the force at the opposite end, and the weight to be lifted between them. 伯莎M.克拉克. 科学通论.
• Let the lever, any strong metal bar, be supported on a stone which serves as fulcrum; then if a man exerts his force at the end of the rod somewhat as in Figure 91 (p. 伯莎M.克拉克. 科学通论.
• The force is 2 feet from the fulcrum, and the weight (4) is 1 foot from the fulcrum, so that Force × distance = Weight × distance, or 2 × 2 = 4 × 1. 伯莎M.克拉克. 科学通论.
• The distance from the force to the fulcrum is called the force arm. 伯莎M.克拉克. 科学通论.
• If the load is halfway from the fulcrum to the man's hands, the man will have to lift with a force equal to one half the load. 伯莎M.克拉克. 科学通论.

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