Labor-saving lever means that the power arm is greater than the resistance arm, and the power is less than the resistance when balancing. That is to say, when the length of the moment arm (with the fulcrum o as the dividing line) is greater than the length of the resistance arm, the power is small and labor is saved.

Let the power arm be L 1, the resistance arm be L2, and L 1×F 1=L2×F2. When L 1 is greater than L2, it is a labor-saving lever, that is, L 1 > L2, then F1

Analyzing the process of tiptoe, the human lever rotates around the foot O, the center of gravity is at the foot B, the gastrocnemius strength is at the ankle A, and the strength arm is larger than the resistance arm, so tiptoe belongs to labor-saving lever.

Extended data:

1, laborious lever:

Features: laborious and distance-saving power arm is shorter than resistance arm, and the power is greater than resistance, so it can be called laborious lever.

Formula: when L 1×F 1=L2×F2, l1; F2 .

2. Equal arm lever:

Features: the power arm is as long as the resistance arm, which is neither labor-saving nor laborious, nor saves distance.

Formula: when L 1×F 1=L2×F2, L 1=L2, then F 1=F2.

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