Mechanical devices that can alter the direction or amount of a force are known as simple machines. It’s a tool that makes labour easier by reducing effort, speeding up motion, applying force at a convenient location, or lowering the risk of a dangerous operation. To multiply force, they employ leverage or mechanical advantage. There are few or no moving parts in it.

Terms related to simple machines

1. Load (L): The Load is a resistive force that must be resisted by a machine. Newton is the SI unit (N).
2. Effort (E) is a term used to describe an external force provided to a simple machine to overcome a load. Newton is the SI unit (N).
3. Fulcrum (Pivot, F): The pivot or support point for something.
4. Mechanical advantage (MA): is defined as the ratio of Load (L) to the magnitude of Effort (E).

MA = Load Arm (L) / Effort Arm (E)

The distance in between effort (force) and the Fulcrum is called the Effort Arm (E).

The distance in between load and the fulcrum is called the load arm (L).

Lever

The lever is a machine that has a simple design and is made out of a stiff rod or beam that is attached to a fixed hinge called the fulcrum. The fulcrum is the point at which the lever is located, and it either turns or maintains the lever. This is then employed to apply a force to a load that is mechanically beneficial. A lever is a construction that can revolve around a central axis. This construction comes in three varieties: first-class lever, second-class lever, and third-class lever. The fulcrum, the force, and the load are used to classify them.

The mechanical advantage of a lever is defined as the quantity by which a certain mechanism multiplies a force applied. The type of lever and the amount of mechanical advantage the machine has can be computed or determined by evaluating the location of the load, effect, and fulcrum. The load becomes easier to shift when the effort is more away from the fulcrum. It is equal to the ratio of the load’s effort to the distance between the fulcrum’s effort and the load’s distance. There is a mechanical advantage in the lever if the distance of effort to the fulcrum is greater than the load of the fulcrum’s distance.

Types of levers

First class lever: 

The fulcrum of this sort of lever is located between the weight and the force exerted. The force-fulcrum-weight order is used to depict it. The most basic form of lever is this one.

Examples:

1. Seesaws, crowbars, or our hand pressing an object
2. The use of scissors entails the application of two first-class levers.
3. Another example is a wheel and axle.
4. A first-class lever is also removing a nail from a hardwood plank.

Seconds class lever:

The pivot is at one end, while the force is applied at the other. The weight is in the centre of these two options. This would be in the following order: fulcrum-weight-force. The use of force at one end will result in some work being done at the other. 

Examples: 

1. Wheelbarrow
2. Staplers
3. Doors or gates
4. Bottle openers
5. Nutcracker
6. Nail clippers

Third class lever

The pivot is at one end of the lever, the force is delivered in the middle, and the weight is at the other end. A weight-force-fulcrum is used to express the order. In this situation, we must expend more energy to move the weight over a greater distance. 

Examples:

1. Fishing rod
2. Baseball bat
3. Human jaw
4. Broom
5. Bow and arrow

Conclusion

Simple machines usually have a small number of moving parts, if any at all. It alters the speed and quantity of a force to make tasks easier to accomplish. Simple machines include the inclined plane, lever, wedge, wheel and axle, pulley, and screw.