A lever is also one of the simple machines. It consists a board or bar that rests on a turning point. This turning point is called the fulcrum. An object that a lever moves is called the load. The closer the object is to the fulcrum, the easier it is to move.
There are three classes of levers:
Classes of Levers
First-class levers have the fulcrum placed between the load and the effort, as in the seesaw, crowbar, and balance scale. If the two arms of the lever are of equal length, as with the balance scale, the effort must be equal to the load. If the effort arm is longer than the load arm, as in the crowbar, the effort travels farther than the load and is less than the load.
Second-class levers have the load between the effort and the fulcrum. A wheelbarrow is a second-class lever. The wheel’s axle is the fulcrum, the handles take the effort, and the load is placed between them. The effort always travels a greater distance and is less than the load.
Third-class levers have the effort placed between the load and the fulcrum. The effort always travels a shorter distance and must be greater than the load. A hammer acts as a third-class lever when it is used to drive in a nail: the fulcrum is the wrist, the effort is applied through the hand, and the load is the resistance of the wood. Another example of a third-class lever is the human forearm: the fulcrum is the elbow, the effort is applied by the biceps muscle, and the load is in the hand.
Learn more: The working principle of the lever is based on Newton's laws of motion and modern theories of statics. We know that the total work done is a product of force and distance. A load is the physical object that is being lifted. A fulcrum in a lever is the thing that helps in making the load lighter. An effort is the person who pushes or pulls to move the object. The distance between the fulcrum and point of effort is called 'effort arm' and that between fulcrum and the load is called 'load arm'. Thus the Law of the Lever can be defined by the formula: (Load arm) × (Load force) = (Effort arm) × (Effort force)
The Inclined Plane and the Lever-The Lever
A lever is also one of the simple machines. It consists a board or bar that rests on a turning point. This turning point is called the fulcrum. An object that a lever moves is called the load. The closer the object is to the fulcrum, the easier it is to move.
There are three classes of levers:
Classes of Levers
First-class levers have the fulcrum placed between the load and the effort, as in the seesaw, crowbar, and balance scale. If the two arms of the lever are of equal length, as with the balance scale, the effort must be equal to the load. If the effort arm is longer than the load arm, as in the crowbar, the effort travels farther than the load and is less than the load.
Second-class levers have the load between the effort and the fulcrum. A wheelbarrow is a second-class lever. The wheel’s axle is the fulcrum, the handles take the effort, and the load is placed between them. The effort always travels a greater distance and is less than the load.
Third-class levers have the effort placed between the load and the fulcrum. The effort always travels a shorter distance and must be greater than the load. A hammer acts as a third-class lever when it is used to drive in a nail: the fulcrum is the wrist, the effort is applied through the hand, and the load is the resistance of the wood. Another example of a third-class lever is the human forearm: the fulcrum is the elbow, the effort is applied by the biceps muscle, and the load is in the hand.
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Learn more: The working principle of the lever is based on Newton's laws of motion and modern theories of statics. We know that the total work done is a product of force and distance. A load is the physical object that is being lifted. A fulcrum in a lever is the thing that helps in making the load lighter. An effort is the person who pushes or pulls to move the object. The distance between the fulcrum and point of effort is called 'effort arm' and that between fulcrum and the load is called 'load arm'. Thus the Law of the Lever can be defined by the formula: (Load arm) × (Load force) = (Effort arm) × (Effort force)
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