How does a lever work? Section 5-3

Levers A lever is a bar that is free to turn about a fixed point called the fulcrum which supports the lever. A lever increases force and makes the work easier. Every lever has an effort arm ( dist. from effort force to fulcrum) and a resistance arm (dist. from resistance force to fulcrum).

MA = effort arm length/resistance arm length. Mechanical Advantage MA = effort arm length/resistance arm length.

First-class levers The fulcrum is between the effort and the resistance. Crowbar, hammer, scissors.

First-class levers

Second-class levers The resistance is between the effort and the fulcrum. Wheel barrel, bottle opener, nut cracker.

Second-class levers

Third-class levers The effort is between the fulcrum and the resistance. Bat, fishing pole, tennis racket, tweezers, shovel.

Third-class levers

H.W. p.81 check/apply 1-8 wkst. 5-3 p. 81 activity lever lab