Simple machines are mechanical devices that are used to make work easier. Combinations of two or more simple machines working together are called compound machines.
These machines create systems for different kinds of movement to occur when force is applied to a load. Both simple and compound machines make work easier by changing the size or direction of the force. There are six standard types of simple machines.
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 simple machine made of a rigid beam and a fulcrum. The effort (input force) and load (output force) are applied to either end of the beam. The fulcrum is the point on which the beam pivots.
When an effort is applied to one end of the lever, a load is applied at the other end of the lever. This will move a mass upward. Levers rely on torque for their operation. Torque is the amount of force required to cause an object to rotate around its axis (or pivot point).
Based on the locations of fulcrum, load, and effort, the lever is divided into three types. Also, leverage is a mechanical advantage gained in a system. It is perfect for lifting or moving heavy things.
A lever is simply a plank or ridged 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.
Parts of a lever
There are three parts to all levers:
- Fulcrum – the point at which the lever rotates.
- Input force (also called the effort) – the force applied to the lever.
- Output force (also called the load) – the force applied by the lever to move the load.
The beam is simply a long plank. It may be wood, metal, or any durable material. The beam rests on a fulcrum (a point on the bar creating a pivot).
When you push down one end of a lever, you apply a force (input) to it. The lever pivots on the fulcrum and produces an output (lift a load) by exerting an output force on the load.
A lever makes work easier by both increasing your input force and changing the direction of your input force.
Principal of Lever
A lever works by reducing the amount of force needed to move an object or lift a load. A lever does this by increasing the distance through which the force acts. Instead, they make the work easier by spreading out the effort over a longer distance.
It has been practically found that when two equal forces acting in opposite directions, i.e., clockwise and counterclockwise, are applied to a uniform lever at equal distances from the fulcrum, they counteract each other and establish a state of equilibrium in the lever.
The experiment has also shown that two unequal forces act in opposite directions. That will bring the magnitude of a force when the magnitude of one force. And its effort arm or lever arm is equal to the product of the magnitude of the other force and the effort arm.
In physics, the product of a force is called the moment of force by its effort. The general principle, known as the theory of moments, states that equilibrium is reached when the sum of the moments of the forces acting in a counterclockwise direction is equal to the sum of the moments of the forces acting in a clockwise direction.
It is possible, as a result, to overcome a very large force at a large distance with a very small force at a large distance from the fulcrum. Archimedes is believed to have a lever in his brain, which gave him a standing place to move the world.
Still confused about the use of a lever and how it works? let’s break it down into pieces for a better understanding.
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. In using a screwdriver to lift the lid from a paint tin you are moving the effort over a greater distance than the load. By having the fulcrum (the rim of the tin) close to the lid (the load) a larger force can be applied to the load to open the tin.
This means you are reducing the effort required, this is what first-class levers do best. Other examples of first-class levers are pliers, scissors, a crowbar, a claw hammer, a see-saw, and a weighing balance.
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.
Archimedes referred to a first-class lever in his famous quote “Give me one firm spot on which to rest (a fulcrum) and I will move the Earth”
Example:
- Our hand 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.
In second-class levers, the load is between the effort (force) and the fulcrum. A common example is a wheelbarrow where the effort moves a large distance to lift a heavy load, with the axle and wheel as the fulcrum.
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.
In a wheelbarrow, the closer the load is to the wheel, the greater the mechanical advantage. Nutcrackers are also 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.
With third-class levers, the 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 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!
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. The load is on the hand, and the effort is 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 usually is 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.
- Wheel bars 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?
Levers are machines used to increase force. We call them “simple machines” because they have only two parts, the handle, and the fulcrum. The handle or bar of the lever is called the “arm”, it’s the part that you push or pull on. The “fulcrum” is the point on which the lever turns or balances.
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.