A pair of plier and scissor are together considered as a _______ Class 1 lever.

Explanation:

Levers are classified into three types or class based on the position of load and effort on the fulcrum

Double Class 1 Lever:

• When we say that pliers and scissors are considered "double Class 1 levers," we refer to the fact that each tool consists of two lever arms working together around a common fulcrum.
• Pliers: Each handle and jaw can be viewed as a separate Class 1 lever. Both levers share the same fulcrum (the joint), and they work simultaneously to grip or cut.
• Scissors: Similarly, each blade and handle of the scissors acts as a separate Class 1 lever. The two levers pivot around the same fulcrum (the joint), working together to achieve the cutting action.
• Examples: Nutcracker, Bolt Cutters, Tin Snips/Shears etc.

Class 1 Lever:

• A Class 1 lever has the fulcrum placed between the effort and load.
• The movement of the load is in the opposite direction of the movement of the effort.
• E.g. crowbars, scissors, pliers, tin snips, and seesaws
• A pair of pliers and scissors are together considered as a double Class 1 lever.

Class 2 Lever

• A Class 2 lever has the load between the effort and the fulcrum.
• In this type of lever, the movement of the load is in the same direction as that of the effort.
• E.g. nutcrackers, wheelbarrows, doors, and bottle openers

Class 3 lever

• A Class 3 lever has the effort between the load and the fulcrum.
• Both the effort and load are in the same direction.
• E.g. tweezers, arm hammers, and shovels.