Which of the following serves as an illustration of a first-class lever__________________?
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Answer: D. all of the above
Explanation
A first class lever requires the fulcrum to be located directly between the applied effort and the load. Human arm movements feature the elbow joint serving as a fulcrum between muscle insertion and hand loads. Scissors and clinical tongs operate with central pivot pins acting as fulcrums separating input forces from output tasks. Simple machines use mechanical advantage to multiply input forces and change the direction of applied work. Levers are categorized into three distinct classes depending on the relative positions of the fulcrum, effort, and load. First class levers can achieve either a mechanical advantage greater than, equal to, or less than one.
Option A is correct but incomplete because scissors and tongs also represent first-class levers. Option B correctly describes a pair of scissors but ignores the mechanical function of human arms and clinical tongs. Option C is valid, yet selecting it exclusively would ignore the other two equally correct mechanical examples.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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