How to Find Mechanical Advantage

Mechanical advantage is a word that is used to explain how much force that is employed internally by any kind of mechanical device. The mechanical advantage permits the device to execute the task for which it was developed. Many common tools that are utilized in the home and in construction make use of this principle.

How to Find Mechanical Advantage


One of the ways to know the idea of mechanical advantage is always to consider the simple action that occurs between a screwdriver and a screw. Force is applied on the screwdriver, causing the body of the tool to rotate although at the same time pushing the screw into some type of surface, for example a wooden block. The mixture of rotational force and forward movement make it feasible for the screwdriver to make use of mechanical advantage to secure the screw into the medium.

Mechanical Advantage of a Lever

The lever is among the six simple machines. It consists of a board or rigid item that pivots around a fulcrum. The lever functions by transferring an applied force over a distance and exerting an output force on an object. The lever raises the magnitude of the output force through sacrificing the distance this force is utilized over. The performance of the lever can be demonstrated by calculating the mechanical advantage (MA) for the lever.

The mechanical advantage of a lever is actually the ratio of the length from the lever on the utilized force side of the fulcrum to the length of the lever on the resistance force side of the fulcrum. You can find 3 basic types of lever.

1.  Lever of the first order

In this kind of lever, the fulcrum is in the center between the load and the effort. An example of this kind of lever is a crowbar. Another is the seesaw.

2.  Lever of the second order

In this kind of lever, the load is in the center, between the effort and the fulcrum. An example of this type of lever is a wheelbarrow.

3.  Lever of the third order

In this type of lever, the energy is in the center, between the load and the fulcrum. An example of this type is actually the human arm, in which the elbow is the fulcrum and the biceps muscles are the energy, and the hand (and whatever it is holding) is actually the load.

Calculating the Mechanical Advantage in a Lever

Determine the fulcrum. This would be the point of which the board or rigid item pivots around.

Determine the locations of the input and output forces. The input force is actually the force that is put on the lever, frequently by a machine or human. The output force is the force that the lever exerts on to an object.

Locate the distance between the fulcrum and the input force. This is called the resistance arm.

Locate the distance from the fulcrum to the output force. This is referred to as the effort arm.

Divide the length of the effort arm from the length of the resistance arm to calculate mechanical advantage.

MA = L (effort arm) / L(resistance arm)

Mechanical Advantage of a Pulley

A pulley, which is based on the Greek word polos, which means axis, is a wheel having a groove. A belt, rope or cable works inside the groove. That mechanism can be employed alone or linked to other pulleys in a pulley system.

The more the number of pulleys within the system, the less force it will require to lift an object. Attempt to lift a 50-pound boulder with just your arms and then make use of a pulley to pick it up. The pulley makes lifting the boulder simpler because it decreases the effort needed to lift. However notice that, even though lifting gets easier, you pull a rope that moves a greater distance compared to height to which you lift the boulder.

This additional distance reduces your effort by providing you a mechanical advantage. The mechanical advantage of a pulley is equal to the amount of ropes that help the moveable pulley. (When calculating the mechanical advantage of a pulley, count each end of the rope like a separate rope). You can calculate this number for any pulley system using the following techniques.

Calculating the Mechanical Advantage in a Pulley

Find the mechanical advantage of any pulley system by noting the number of doubled-up stretches of rope or line must shorten for that load to be lifted. Denote it with the letter n. For instance, if the line moves between two blocks of pulleys 4 times then n=4. Proceed to Step 3.

Find the mechanical advantage of a leverage system by noting how long the load's point of contact on the lever is through the fulcrum. Denote it L. Note how long the force input's point of contact on the lever is from the fulcrum. Denote it F.

Calculate n = F/L.

Write n like a ratio of integers. For instance, if n=1.5, then write 3:2, because 3/2 is equivalent to 1.5.

This is the mechanical advantage of the system.

Mechanical Advantage of a Wedge

A wedge is a triangular designed tool, a compound and portable inclined plane and one of the 6 simple machines. It can be utilized to separate two objects or portions of an object, maintain an object in place or lift up an object.

It functions by changing a force used to its blunt end into forces perpendicular (normal) to its inclined surfaces. The mechanical advantage of a wedge is provided by the ratio of the length of its slope to its width. Even though a short wedge with a broad angle may do a job quicker, it requires more force compared to a long wedge with a narrow angle.

The mechanical advantage of a wedge can be calculated by separating the length of the slope from the wedge's width:

Mechanical Advantage = Length/Width

The greater acute or narrow, the angle of a wedge, the more the ratio of the length of its slope to its width and thus the greater mechanical advantage it will yield.

But, in an elastic material for example wood, friction may bind a narrow wedge more effortlessly than a wide one. This is why the head of a splitting maul features a much wider angle compared to that of an axe.