3-3 How does a lever work?
OBJECTIVES: Explain how a lever makes work easier. Describe the three classes of levers.
Key Terms
lever: bar that is free to turn around a fixed point
fulcrum: fixed point around which a lever pivots or turns
Lesson Summary
• A lever is a bar that is free to turn around a fixed point called a fulcrum.
• The distance from the effort force to the fulcrum is the effort arm.
• The distance from the resistance force to the fulcrum is the resistance arm.
• The mechanical advantage of a lever is equal to the length of the effort arm divided by the length of the resistance arm.
• There are three classes of levers. The classes are based on the position of the resistance force, the effort force, and the fulcrum.
Key Terms
lever: bar that is free to turn around a fixed point
fulcrum: fixed point around which a lever pivots or turns
Lesson Summary
• A lever is a bar that is free to turn around a fixed point called a fulcrum.
• The distance from the effort force to the fulcrum is the effort arm.
• The distance from the resistance force to the fulcrum is the resistance arm.
• The mechanical advantage of a lever is equal to the length of the effort arm divided by the length of the resistance arm.
• There are three classes of levers. The classes are based on the position of the resistance force, the effort force, and the fulcrum.
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