Thank God for the trolleys at the airport. How else will you be able to move your luggage around? Think of the many things you do so easily with a simple machine or tool. They would have been hard and tiring to do manually.

For example, opening a bottle, cutting a piece of cloth or splitting wood. This is all possible because of simple machines.

In this article, you will learn the definition of a simple machine and the types of simple machines.

What is a Simple machine?

A simple machine is a machine that makes work easier by reducing the amount of force needed to do the work. They allow you to do heavy work with little effort. The little effort or force you apply is converted into a larger force that does the work.

Simple machines have simple makeup. They consist of a few or no moving parts.

Deep Dive – Work is the force applied on an object to move it over a distance. Machines help us do work by applying a small force over a large distance.

Some examples of simple machines are wheelbarrows, scissors, axes, mouse traps, bottle openers etc. 

Let’s move on to the types of simple machines.

Types of Simple Machine

There are six types of simple machines.

1. Levers
2. Wheel and axle
3. Pulley
4. Inclined plane
5. Wedge
6. Screw

The six types of simple machines can be grouped into two. The inclined plane, wedge and screw work using a sloped surface. While the lever, wheel and axle and screw work by changing the direction of a force at a pivot point.

Let’s see what each is about.

Lever

A lever is made up of a bar or a rod placed on a fixed support. The fixed support is called a fulcrum. 

When you are using a lever, you are applying a small force over a long distance. The lever takes the force, converts it into a larger force and applies it over a short distance. The figure below shows what a lever looks like.

Figure 1: A Lever

You may notice that the figure above looks like a seesaw. This is because a seesaw is an example of a lever. Other examples include crowbars, wheelbarrows, tweezers, and staplers. Scissors, bottle openers and many more.

Parts of a lever

As stated earlier, a lever is made up of a rod placed on a fixed support. The fixed support is called the fulcrum. The two ends of the rod are where you place the load and where you apply effort or force. So, the three parts of a lever are:

1. Fulcrum
2. Load arm
3. Effort (force) arm

The load and effort arms can be on either side of the rod. It depends on the type of lever as you will see soon. The figure below explains more.

Figure 2: Parts of a lever

Types or Classes of Lever

There are three types or classes of levers.

1. First-class lever
2. Second-class lever
3. Third-class lever

The difference between the types of levers is the placement or position of their parts. Let’s see what each is about.

First-class lever

The fulcrum is placed between the load and effort arms for a first-class lever. Examples of this class of lever include seesaws, pliers, scissors, claw hammers etc.

Figure 3: First-class lever

Second class lever

The load is placed between the fulcrum and the effort arm for a second-class lever. Examples include wheelbarrows, bottle openers, nail cutters, nut crackers etc.

Figure 4: Second-class lever

Third class lever

For a third-class lever, the effort is between the load arm and the fulcrum. Examples include staplers, tweezers, fishing rods, mouse traps etc.

Figure 5: Third-class lever

Wheel and Axle

A wheel and axle is a wheel with a rod in the middle called an axle. You may have noticed that it is easier to move something when you place it on wheels. For example, using a trolley to move your luggage. This is because the wheels reduce the friction between the ground and the load you are carrying. See the figure below.

Figure 6: Wheel and Axle

Wheel and axle work like a lever. When you apply a small force to the rim of the wheel it is converted to a larger force applied over a shorter distance at the axle. See the figure below.

Figure 7: Diagram showing how force applied is converted over distance in a lever

Examples of wheels and axles include cars, bicycles, pencil sharpeners, doorknobs etc.

Pulley

A pulley is a simple machine with a wheel and a rope wrapped around it. Force is applied to one end of the rope and the other end is tied around the load. 

A pulley works by changing the direction of a force and spreading a small force along a long path. The figure below shows a pulley system.

Figure 8: A pulley system

Many pulleys can be linked together. This will allow you to do more work with less force. The figure below shows a multiple pulley system.

Figure 9: Multiple pulley system

An elevator uses a pulley system. They are also used to raise and lower things like flags, blinds and sails.

Inclined Plane

An inclined plane is a plane with a sloping surface. It is a plane raised to a horizontal angle. One end of the plane is higher than the other which means that you can slide a load up instead of lifting it. This makes the work easier because a small force is spread over a long distance. 

The angle of the inclined plane determines how much force will be used to raise a load. The steeper the angle, the greater the force required to move the load. See the figure below.

Figure 10: Inclined Plane

Inclined planes can be found in slides and ramps.

Wedge

A wedge is used to move two objects apart. It is made up of two inclined planes placed back-to-back. When you apply a small force to the back of the wedge, it is converted to a larger force at the tip of the wedge. See the figure below.

Figure 11: Diagram showing a wedge and where force is applied

Examples of wedges include chisels, knives and axes.

Screw

A screw is a type of inclined plane wrapped around a pole or cylinder. The inclined plane of the screw is the threads. You can use a screw to pull, push and hold things together. When you turn the screw, the thread moves to pull something or to hold materials together. See the figure below.

Figure 12: A screw

Examples of screws include screws, bolts, light bulbs, lids etc.

A lot of the objects we see and use every day are simple machines. The blinds in our homes work using the pulley system. Doors are levers and screws attach sockets to our walls. Simple machines are the basic forms of machines, and they are everywhere.

Key Points.

• A simple machine is a machine that makes work easier by reducing the amount of force needed to do the work.
• There are six types of simple machines.

1. Levers
2. Wheel and axle
3. Pulley
4. Inclined plane
5. Wedge
6. Screw

• The six types of simple machines can be grouped into two. The inclined plane, wedge and screw work using a sloped surface. While the lever, wheel and axle and screw work by changing the direction of a force at a pivot point.
• Simple machines contain few or no moving parts.

FAQs

Q. What is a simple machine?

Ans: A simple machine is a machine that makes work easier by reducing the amount of force needed to do the work.

Q. What are examples of simple machines?

Ans: Some examples of simple machines are wheelbarrows, scissors, axes, mouse traps, bottle openers etc.

Q. What are the types of simple machines?

Ans: There are six types of simple machines. They are the lever, pulley, wheel and axle, inclined plane, wedge and screw.

Quiz

Q. Which of the following is not a type of simple machine?

A. Inclined Plane

B. Screw

C. Plank

D. Lever

Ans. C

Q. A lever works by converting a small force applied over a short distance to a larger force over a short distance. TRUE or FALSE

Ans. True

Q. A wedge is two inclined planes placed back-to-back. TRUE or FALSE.

Ans. True

Q. Which of the following best describes an inclined plane?

A. A simple machine with a wheel and a rope wrapped around it.

B. A bar with fixed support.

C. A plane with a sloping surface.

D. A simple machine with the load placed between the fulcrum and effort.

Ans. A plane with a sloping surface