lever
Definition
A lever is a simple machine that consists of a rigid bar that is free to pivot about a fixed point called the fulcrum. The fulcrum is the point where the lever is supported. The load is the object that is being lifted or moved. The effort is the force that is applied to the lever.
The lever works by using the principle of moments. The moment of a force is the product of the force and the distance from the fulcrum to the point where the force is applied. The moment of the load must be balanced by the moment of the effort for the lever to be in equilibrium.
The amount of force that is required to lift the load is inversely proportional to the distance between the fulcrum and the load. This means that if the distance between the fulcrum and the load is doubled, then the force required to lift the load is halved.
Levers are used in many different machines, such as crowbars, wheelbarrows, and see-saws. They are also used in many everyday objects, such as scissors, tweezers, and bottle openers.
How can the word be used?
Effort: The force that is applied to one end of a lever.
Different forms of the word
Noun: A lever is a simple machine that consists of a long, rigid bar that is pivoted at a fixed point called the fulcrum. When a force is applied to one end of the lever, it moves the other end, which can be used to lift or move a heavy object.
Adjective: Levered is an adjective that describes something that is moved or operated by a lever. For example, a levered gate is a gate that is opened or closed by a lever.
Verb: To lever is to move or operate something with a lever. For example, to lever open a door is to use a lever to open the door.
Etymology
The word "lever" comes from the Old French word "lever", which also means "to raise". It was first used in English in the 13th century.
The Old French word "lever" is thought to be derived from the Latin word "levis", which also means "light" or "easy". This is because a lever can be used to make a heavy object seem lighter, by using a small amount of force to move a large object.
Question
Where might you find a lever?
AQA Science Exam Question and Answer
Question:
Describe the concept of a lever and its application in everyday life. Provide examples of different types of levers and explain how they work.
Answer:
A lever is a simple machine consisting of a rigid bar that pivots around a fixed point called the fulcrum. It operates on the principle of mechanical advantage, allowing us to lift, move, or manipulate objects with less effort. Levers are prevalent in our daily lives and can be found in various objects and activities.
There are three types of levers based on the position of the fulcrum, load, and effort: first-class, second-class, and third-class levers.
First-class levers have the fulcrum placed between the load and the effort. Examples include seesaws and crowbars. These levers can change the direction of the force applied and provide a mechanical advantage when the effort arm is longer than the load arm.
Second-class levers have the load between the fulcrum and the effort. Wheelbarrows and nutcrackers are examples. These levers provide a mechanical advantage by increasing the force applied to the load.
Third-class levers have the effort applied between the fulcrum and the load. Tweezers and fishing rods are instances. While third-class levers do not provide a mechanical advantage in terms of force, they enable finer control over the load.
Levers are integral to our lives, from using scissors to lifting objects with a pry bar. They showcase the elegant way simple machines amplify our strength and manipulate forces to accomplish everyday tasks more efficiently.