Question

Write the answers to the following questions in your own words.
(a) What is meant by simple machines?
(b) Mention the advantages of using a machine.
(c) What is meant by complex machines?
(d) What is a lever ? How are the orders of the lever determined?

Answer 1

(a) Simple machines are the tools that help people work faster and better. These help us lift heavy loads, change the speed of the motion or the direction of force. Examples are simple machines are knife, nutcrackers etc.

(b) The advantages of using a machine are:

• More work can be done in lesser time as well as with great accuracy
• Less effort has to be applied to accomplish the task

(c) A machine made up of two or more simple machines is called a complex machine. It consists of different parts that carry out different task and together contribute to the working of the machine. The most common example is that of a bicycle.

(d) A lever is a simple machine consisting of a rigid rod which is capable of turning around a pivot called a fulcrum. It has three parts, namely, effort, load and fulcrum.

• Fulcrum: The rod of the lever rests on it and the lever rotates about it.
• Load: The weight lifted by the liver is called the load.
• Effort: The force applied on the other end of the rod to lift the load is called the effort.

The orders of the lever are determined depending on the position of the effort, the fulcrum and the load.
Lever of first order: When the fulcrum is situated between load and effort, we call it a lever of first order. For example, beam balance, a crowbar, a see-saw.

Lever of second order: When the fulcrum and effort are situated at the two opposite ends of the lever and a load is placed in between them, we call it a lever of second order. For example, a nutcracker, a wheel-barrow, etc.

Lever of third order: When the fulcrum and load is situated at the opposite ends of the lever and an effort is applied somewhere between them, we call it a lever of third order. For example, a pair of tongs, a fishing rod, etc.