Simple machines are often leveraged to accomplish tasks in a more effortless manner. When combined together to form more complex structures, they are referred to as compound machines.
When a force is exerted on a load, these machines initiate a system for several types of movement which results in work being done. Indeed, both simple machines and compound machines work by changing the amount or direction of force, which makes work relatively easier.
You will find a total of six standard types of simple machines incorporated in your daily life.
They are the:
- Lever
- Wheel and axle
- Pulley
- Inclined plane
- Wedge
- Screw
Let us consider the first of these simple machines: the lever.
What is a Lever?
A lever is a type of simple machine that consists of a rigid beam and a fulcrum. The beam has effort (input force) and load (output force) on both ends of it. The fulcrum refers to the point on which the beam pivots.
Levers work by relying on torque, the force that lifts the mass, and the structure is placed at one end of the lever while the other end is free to move. Rotating or moving the mass makes it get further from the pivot point and thus makes it rotate around it.
There are types of levers depending on the location of the fulcrum, load, and effort, while the lever torque avoids turning the handle attached to a lever.
It allows the use of mechanical performance to manipulate systems, hence eliminating obstacles while moving around indifferent geometry, simplifying obstacles on incoherent systems around heavy objects. As long as the level is free to move around the pivot, these objects become easy to lift.
Everywhere, simple machines can be found, such as levers, while everyday objects help showcase them, like seesaws, crowbars, fishing lines, oars, wheelbarrows, and shovels.
Parts of a lever
There are three parts to all levers:
- Fulcrum – This is the point from which the lever rotates.
- Input force (also called the effort) – The force that is applied to the lever.
- Output force (also called the load) – the force of the lever that tries to move the load.
The beam is simply a long plank made of wood, metal, or any other durable material. The beam rests on a fulcrum, which is a point on the bar (a pivot).
Applying a force on one end of the lever causes rotation on the fulcrum. For example, if you push down one end of the lever, a force (input) is applied to the lever, and the output is lifting a load, which requires an output force to be exerted on the load.
By increasing the input force and thus changing its direction, a lever can make work easier.
Principal of Lever
Levers work by reducing the amount of force required to move an object or lift a load. The lowered amount of effort needed is compensated through increased distance over which the force has to be applied.
It has been practically demonstrated that if two opposing equal forces, clockwise and counterclockwise, are applied to a lever at equidistant positions from the fulcrum, they balance each other and create equilibrium in the lever.
The experiment has also verified that it is possible to consider two opposing unequal forces acting on a lever where one of the forces is the product force with a force whose magnitude is equal to the product of an arm multiplied by the other stated force.
The arm distance between the point of rotation and the line of action of the force will be equal to the other force and effort arm.
In physics, the product of a force is called a moment of force, it is a force applied to a lever. The general principle of the equilibrium state in physics is that the sum of moments of the counter-clockwise force will equal the clockwise force.
As a consequence, overcoming an enormous force at a considerable distance is achievable using only a small force far away from the fulcrum. It is said that Archimedes was able to think of a lever as being in his brain because he had a place where he could stand and move the world.
Types of Lever
There are three types of levers: first-class, second-class, and third-class. The difference between the three classes depends on where the force is, where the fulcrum is, and where the load is.
#1. First-class lever – the fulcrum is in the middle of the effort and the load.
First-class levers have the fulcrum between the force and the load. For example, when using a screwdriver to lift the lid off a tin of paint, you are moving the effort over a greater distance than the load. The rim of the tin acts as the fulcrum, and you can exert a greater force on the lid to open the tin.
In other words, you are applying less effort, which is the main selling point of first-class levers. Other examples of first-class levers include: pliers, scissors, crowbars, claw hammers, see-saws, and weighing balances.
To summarize, in a first-class lever, the effort (force) travels a greater distance in relation to the movement of the load, and the fulcrum is positioned between the effort (force) and the load.
With an increasing ratio of force arm length to load arm length, the mechanical advantage of a first-class lever increases.
Archimedes referred to a first-class lever in his achievement quotation, “Give me one firm spot on which to rest(a fulcrum) and I will move the earth”.
Example:
- Our hands pushing an object or seesaws, crowbars.
- Using scissors represents the use of two first-class levers.
- A wheel and axle is also an example.
- Pulling a nail out of a wooden plank also represents a first-class lever.
#2. Second class lever – the load is in the middle between the fulcrum and the effort.
Second-class levers have the load in the middle, between the effort (force) applied and the fulcrum. A common example is a wheelbarrow, where the effort drives a big distance to lift the load, and the axle and wheel act as the fulcrum.
In a second-class lever, the effort moves a considerable distance to lift the load a small distance. As the ratio of the length of the effort (force) arm to the load arm increases, the mechanical advantage of a second-class lever increases; thus, the advantage of the lever is greater.
In a wheelbarrow, a mechanical advantage is pronounced closer to the wheel. Nutcrackers also serve as an example of a second-class lever.
Example:
- Wheelbarrow
- Staplers
- Doors or gates
- Bottle openers
- Nutcracker
- Nail clippers
#3. Third class lever – the effort is in the middle between the fulcrum and the load.
In third-class levers, effort is between the load and the fulcrum, for example, in barbecue tongs. Other examples of third-class levers are a broom, a fishing rod, and a woomera.
In a third-class lever, the mechanical advantage is low because the force (effort) is less than the distance through which the load moves. It is difficult to apply great force to the load. For example, when one goes to barbecue sausages, it is advantageous not to squish them!
When you lift a load using your forearm, you are using a third-class lever. Your biceps muscles are attached to the forearm just in front of the elbow, which is why the lever is called a third-class one. The hand carries the load while the elbow acts as a fulcrum. The effort is located between the fulcrum (elbow) and the load.
Example:
- Fishing rod
- A broom
- A baseball bat
- A bow and arrow
- Human jaw
Uses of Lever
A lever is usually used to move or lift objects. Sometimes it is used to push against objects, but not move them. Levers can be used to exert a large force over a small distance at one end by exerting only a small force over a greater distance at the other.
Uses of Lever:
- Levers make it easy to lift heavy materials, remove tight objects, and cut objects.
- Hammer claws are common levers that help you remove nails embedded in wood or other hard surfaces.
- Wheelbarrows are helpful every day because they allow you to transport loads that are too heavy or heavy.
- Tweezers and tweezers are examples of levers that make it easy to lift or remove items, even if the items are not heavy.
- Scissors are an example of a lever that uses force to cut or separate material.
FAQs.
What Is A Lever?
A lever is simply a plank or rigid beam that is free to rotate on a pivot. It is perfect for lifting or moving heavy things. It is a useful, simple machine, and you can find them everywhere. Good examples of levers include the seesaw, crowbar, fishing line, oars, wheelbarrows, and the garden shovel.
What Are The Types Of Levers?
There are three types of levers.
1. First-class lever – the fulcrum is in the middle of the effort and the load. First-class lever.
2. Second class lever – the load is in the middle between the fulcrum and the effort. Second class lever.
3. Third class lever – the effort is in the middle between the fulcrum and the load.
What Is A First-Class Lever?
In summary, in a first-class lever, the effort (force) moves over a large distance to move the load a smaller distance, and the fulcrum is between the effort (force) and the load. As the ratio of effort (force) arm length to load arm length increases the mechanical advantage of a first-class lever increases.
What Is A Second-Class Lever?
In a second-class lever, the effort moves over a large distance to raise the load a small distance. As the ratio of effort (force) arm length to load arm length increases, the mechanical advantage of a second-class lever increases.
What Is A Third-Class Lever?
In a third-class lever, the load moves further than the effort (force) and the mechanical advantage is low, which is why it’s difficult to apply great force to the load. This can be an advantage by not squashing sausages on the barbecue!
What are the 10 examples of levers?
Some common examples of first-class levers are a hole punch, pliers, scissors, and a see-saw. Some common examples of second-class levers are a wheelbarrow, bottle openers, nail clippers, and a nutcracker. Some common examples of third-class levers are a shovel, fishing rod, cooking tongs, and tweezers.