Simple Machine

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In today’s class, we will be talking about the simple machine. Enjoy the class!

Simple Machine

The development of simple machines is fascinating helpful because we use them in our everyday life. They make our work easier and faster. A difficult work can be executed without much stress, e.g. lifting of heavy objects, pushing or pulling heavy objects, etc.

A simple machine is an essential mechanical device/tool which allows force (effort) applied at one point to overcome a resistance force (load) at the other end. Generally, a machine enables us to overcome a large resistance or load by applying a small effort or force. Working with a simple machine makes it more convenient than it could be done without it.

Definition of terms used in simple machine

1. Mechanical Advantage (M.A): This is the ability of a machine to overcome a large load/resistance through a small effort. It is the ratio of load to effort applied and it is unitless.
2. Velocity Ratio (V.R): This is a ratio of the distance moved by the effort to the distance moved by a load, in the same interval. It is also unitless.
3. Efficiency (Er): This is the ratio of the Useful work done by the machine to the work put into the machine. It is expressed as a percentage. The efficiency of a machine can never be 100% because part of the effort applied is used to overcome friction.

Types of simple machine

There are six types of simple machines:

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

• Lever:

A lever is a machine, which consists of a rigid rod supported at the fulcrum/pivot about which it can rotate freely. With this machine, we can overcome a large resistance/load by application of small force at one end. There are three types of lever: first-class lever, second-class lever and third-class lever.

• Wheel and axle:

Wheel and axle is a simple machine that consists of a round cylindrical drum (wheel) around which a rope is wound. It is used to lift water from deep well or raise heavy loads.

• Inclined plane:

Inclined plane is a type of machine used to raise heavy loads such as drums of oil, up a sloping plank to the high floor. The plank will make an angle with the horizontal floor.

• The wedge:

Wedges are sometimes considered as inclined planes, they are used to separate bodies which are held together by a large force. Examples of wedges include chisel, axe, knife, shovel, scissors, etc.

• The pulley system:

This is a fixed wheel hung on suitable support with a rope passing round its groove. Pulleys are used in construction sites to raise or lower heavy loads.

• The screw:

This is an inclined plane wrapped around a cylinder. It is used to fasten two or more objects together.

Uses of simple machine

Some of the uses of the simple machine are:

1. They make our work easier by reducing the amount of effort we need to perform certain tasks.
2. Simple machines are used to move an object from one point to another.
3. They are used in more complex machines.
4. They are used to change the direction of the force on an object.

 

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