## Simple Machine

Subject: Science

#### Overview

Simple machines are simple in structure which makes our work easy, efficient and more convenient. This note provides information about a simple machine with its types, activities, and importance.

### Introduction

We use various types of machine in our daily life to perform various activities. These machines make our work easy and efficient. For example, we use a knife to chop vegetables, scissors to cut papers, beam balance to measure weight, bottle opener to open the bottle, etc. There are a simple machine and complex machine. Forceps, punching machine, crowbar, bottle opener, etc. are examples of the simple machine while motorcycle, truck, car, etc. are some examples of the complex machine. A simple machine is a device, which is simple in structure and makes our daily work easier, faster and more convenient.

### Types of Simple Machines

Mainly, there are six types of simple machines, which are given below,

• Lever
• Wheel and axle
• Screw
• Pulley
• Inclined plane
• Wedge

#### Lever

Lever is a type of simple machine that is used to lift the heavy loads. It is made of a rigid bar that moves about a fixed point called fulcrum. It consists of three parts, effort arm, fulcrum and load arm. Fulcrum is the point where rigid bar rotates. By applying effort in effort arm the load is lifted by the help of fulcrum. Effort arm is the distance between the fulcrum and the point where effort is applied and load arm is the distance between fulcrum and load where the load is kept. Input work is equal to output work in an ideal lever which is the balanced condition of the lever. It is the principle of the lever.
Levers are of three types depending upon the positions of fulcrum, load, and effort which are as follows,

1. First class lever: In the first class lever, fulcrum lies between effort and the load. Effort arm is longer than load arm. Beam balance, scissors, crowbar, etc are some examples of the first class lever.
2. Second class lever: In the second class lever, the load is placed between the fulcrum and the effort. Since effort arm is longer than load arm it multiplies the applied effort which helps to lift the heavy load by applying small effort. Wheel-barrow, nut- cracker, paper- cutter, etc. are some examples of the second class lever.
3. Third class lever: In the third class lever, the effort is located in between fulcrum and load. Here, effort arm is shorter than the load arm. It cannot lift the heavy load but increases the speed of doing work. Fire tongs, fishing rod, shovel, etc. are the examples of the third class lever.

Activity 1

Bring a rigid bar, one heavy stone, and two bricks. Then, lift the stone without using a rigid bar. Place stone in the one end of the bar and place the middle part of the bar in the bricks of a certain height. Then, apply the effort on the other end of the bar. What do you conclude from this experiment? What is the reason behind it?

#### Pulley

A pulley is a simple machine consisting grooved circular disc and a rope. The rope passes over the circular disc. In pulley, a load is attached to one end of the rope while the effort is applied at the another end of the same rope. Here, the effort is applied in a convenient way which makes our work easier. There are two types of the pulley on the basis of their movements. They are as follows,

1. Fixed pulley: In fixed pulley, the pulley remains in the same position or fixed at the point while the pulley’s wheel moves with the rope that passes through it while raising the load. It is used to lift water from well. It is also used in flag poles.
2. Movable pulley: In movable pulley, the pulley moves with the load. Both load and pulley move upward when the rope is moved upward. One end of the rope is fixed at one point and effort is applied to another point. Here, applied effort is equally shared by both parts of the rope due to which we can lift the load two times heavier than the applied effort. For example, we can uplift the load of 20N by applying 10N effort.

Activity 2

Lift the water from the well by using a pulley. The water bucket moves upward though you are pulling the rope downward. What do you conclude from this experiment? What is the reason behind this?

#### Wheel and axle

It consists of two cylinders having a different radius. Cylinder with a small radius is axle and cylinder with a large radius is a wheel. Formally, a rope is coiled in wheel and axle. The effort is applied in wheel and load in the axle. They move in the same manner but the distance covered is different due to the difference in radius. Since effort applied on the wheel is magnified so, by applying small effort on the wheel, heavy loads can be lifted. Some of the examples of wheel and axle are paddle of the bicycle, a drill used by carpenters, steering of vehicles, etc.

Activity 3

Ride and use the paddle of the bicycle. You can find that the tyres move faster though you paddle slowly. What do you conclude from this experiment? What is the reason behind this ?

#### Inclined plane

It is very difficult to load heavy things onto a truck or some area of a certain height. A huge effort is needed. In such case, the inclined plane is used. It is a sloping surface or a wooden plank. It multiplies the applied effort. It helps to push the heavy load upward easily. The winding road, staircase, ladder, etc. are the examples of an inclined plane.

Activity 4

Bring a sloping surface or a wooden plank and a heavy load like a small drum. Then lift the drum up to the certain height without using the wooden plank. After this, again lift the drum in the same height by using wooden plank i.e. inclined plane. What do you conclude from this two activity? What is the reason behind it?

#### Screw

A screw is an inclined plane wrapped around a nail. It consists of circular edges called thread. The pitch is the distance between two screw thread. The effort is applied to the head of the screw. It looks similar to nail and requires less effort to insert into the wood. Screw, nail, jack screw, etc.are some of the examples of the screw.Jack screw is used to lift the vehicles up to the certain height.

Activity 5

Bring a screw and the wood. Then insert the screw in the wood by rotating its head instead of pressing it inside. The screw moves downward though we don’t press the screw. What is the reason behind it?

#### Wedge

A wedge is a triangular shaped tool. Wedge consists of two or more sloping surfaces with one end sharp or pointed edge while the other one is a blunt edge. Here, the effort is applied at the blunt side. It is mainly used for cutting and splitting things, drilling holes etc. Some of the examples of wedges are axe, knife, nail, sickle, etc.

Activity 6

Bring a knife and a small piece of wood. Then cut the piece of wood with the help of the knife. Though you hit the piece of wood in the straight direction or apply force in one direction (vertical), the woods gets separated (horizontal force). What is the reason behind it?

Activity 7

Identify the simple machines given below. Classify them and write down their uses and types. What do you learn from this activity? Write down your conclusion.

 S.N. Names of simple machine Types of Simple machine Uses

### Importance of Simple Machine

The importances of simple machine is as follows:

• It can transfer force from one place to another.
• It increases the amount of a force so that we can lift heavier objects or exert greater force with the help of a simple machine.
• It can change the direction of the force so that we can move objects in another direction.
• It increases the distance and speed of force so that we can move things farther and faster.
• The simple machine makes our work easy, fast and more convenient.
##### Things to remember
• Lever is a type of simple machine that is used to lift the heavy loads.
•  In the first class lever, fulcrum lies between effort and the load.
• A pulley is a simple machine consisting grooved circular disc and a rope.
• A screw is an inclined plane wrapped around a nail.It consists of circular edges called thread.
• A wedge is a triangular shaped tool. Wedge consists of two or more sloping surfaces with one end sharp or pointed edge while the other one is a blunt edge.

• It includes every relationship which established among the people.
• There can be more than one community in a society. Community smaller than society.
• It is a network of social relationships which cannot see or touched.
• common interests and common objectives are not necessary for society.
##### Simple Machine

Any five types of simple machine with two example of each are given below,

1. Lever
Examples: see- saw and nut- cracker
2. Wheel and axle
Examples: screw- driver
3. Inclined plane
4. Screw
Examples: nail and driller
5. Wedge
Examples: sickle and knife

A lever is a rigid bar which moves freely about a fixed point called the fulcrum. There are three types of lever which are as follows,

1. First class lever
Examples: Beam balance and see- saw
2. Second class lever
Examples: Wheel- barrow and nut- cracker
3. Third class lever

The work done on a machine is called the input work and the useful work done by the machine is called the output work. The principle of lever is given below,
In ideal lever when it is in balanced condition then,
Input work = output work
Or, Effort $\times$ effort arm = Load $\times) load arm. A wedge is a simple machine having two or more sloping surfaces that taper either to form a sharp edge or pointed edge. Any three examples of wedge are axe, knife, and needle. Any three advantages of using simple machines in our daily life are as follows, • It makes or work easier, faster and more convenient. • It increases the amount of a force so that we can lift heavier objects or exert greater force with the help of simple machine. • It change direction of the force so that we can move objects in another direction. A pulley is a simple machine having a grooved circular disc over which a rope passes. There are three types of pulley which are as follows, 1. Fixed pulley: In fixed pulley, the pulley does not move as the load is raised. It is used to lift water from the well. 2. Movable pulley: If the pulley moves along with the load, then it is called movable pulley. Construction crane and modern elevator are the examples of movable pulley. 3. Combined pulley: Combined pulley is a type of pulley that consists of the combination of fixed pulley and movable pulley. Crane used to lift heavy objects is an example of combined pulley. A second class lever is a type of lever in which load is situated between the fulcrum and the effort. Since in bottle opener, the load ( bottle cork) is situated between the fulcrum and effort so the bottle opener is a second class lever. Simple machines: Beam- balance, nut- cracker, flag pole, screw- driver, ladder, nail and axe. The simple machines with their types are given below, • Beam- balance: first class lever • Nut- cracker: second class lever • Flag pole: fixed pulley • Screw- driver: Wheel and axle • Ladder: inclined plane • Nail: screw • Axe: wedge Any five simple machines used in our homes are as follows, 1. Knife: It is used to cut vegetables. 2. Beam- balance: It is used to measure the weight or mass. 3. Bottle- opener: It is used to open the cork of the bottle. 4. Paper- cutter: It is used to cut the papers. 5. Lemon- squeezer: it is used to squeeze the lemon. In second class lever, load is situated between the fulcrum and the effort and in third class lever the effort is situated between the fulcrum and the load. Since in shovel, the effort is situated between the fulcrum and load so it is called third class lever but not a second class lever. The differences between simple machines and complex machines are as follows,  Simple machines Complex machines They are simple in structure. They are complex in structure. Their mechanism is very simple and is very easy to understand and operate. Their mechanism is very complex which is difficult to understand and operate. Examples: scissors and beam balance Examples: car and truck The differences between first class lever and third class lever are as follows,  First class lever Third class lever In the first class lever, the fulcrum is situated between the effort and the load. In the third class lever, the effort is situated between the fulcrum and the load. Effort arm of a first class lever is longer than the load arm. Effort arm of a third class lever is shorter than the load arm. Example: beam balance and see- saw. Example: fishing rod and shovel. The differences between input work and output work are as follows,  Input work Output work The work done on a machine is called input work. The useful work done by a machine is called output work. It is done by the persons. It is done by the machine. Example: flour, salt, and eggs are put in a machine by men to makes noodles. Example: Noodles are made by machine using flour, salt, and eggs The differences between fixed pulley and movable pulley are as follows,  Fixed pulley Movable pulley Fixed pulley is a type of pulley in which pulley does not move with the load. Movable pulley is a type of pulley in which pulley moves along with the load. It does not multiply the force. It multiplies the force. Examples: pulley used to lift the water from the well. Examples: pulley used in construction crane and modern elevators. Solution: We have, Load = 100N Load arm = ? Effort = 25N Effort arm = 25cm Now, by using principle of lever Input work = Output work Or, Effort \(\times$ effort arm = Load $\times$ load arm
Or, 25 $\times$ effort arm = 100 $\times$ 25
Or, Effort arm = $\frac{100 \ times 25}{25}$
Or, Effort arm = 100cm
$\therefore$, The load arm is 100cm.

Solution:
We have,
Effort = 25N
Effort arm = 20cm
Now, by using principle of lever
Input work = Output work
Or, Effort $\times$ effort arm = Load $\times$ load arm
Or, 25 $\times$ 20 = load $\times$ 25
Or, Load = $\frac{25 \ times 20}{25}$
$\therefore$, The load is 25N.

Solution:
We have,
Effort arm = ?
Effort = 50N
Now, by using principle of lever
Input work = Output work
Or, Effort $\times$ effort arm = Load $\times$ load arm
Or, 50 $\times$ effort arm = 75 $\times$ 100
Or, effort arm = $\frac{ 75 \times 100}{50}$
Or, effort arm = 150cm
$\therefore$, The effort arm is 150cm.

Solution:
We have,
Effort arm = 20cm
Effort = ?
Now, by using principle of lever
Input work = Output work
Or, Effort $\times$ effort arm = Load $\times$ load arm
Or, Effort $\times$ 20 = 100 $\times$ 50
Or, Effort = $\frac{ 100 \times 50}{20}$
Or, Effort = 250N
$\therefore$, The effort applied is 250N

Solutions:
We have,
Effort arm = 20cm
Effort = 10N
Now, by using principle of lever
Input work = Effort $\times$ effort arm
= 10 $\times$ 20
= 200.
Output work = Load $\times$ load arm
= 25 $\times$ 5
= 50.
$\therefore$, The input work is 200 and output work is 50.

Solution:
We have,
Effort arm = 10cm
Effort = 5N
Now, by using principle of lever
Input work = Output work
Or, Effort $\times$ effort arm = Load $\times$ load arm
Or, 5 $\times$ 10 = 50 $\times$ load arm
Or, load arm = $\frac{ 5 \times 10}{50}$
$\therefore$, The load arm is 1m.

Now,
Input work = effort arm $\times$ effort
= 10 $\times$ 5
= 50.

Output work = load arm $\times$ load
= 2 $\times$ 50
= 100.
$\therefore$, The input work is 100 and output work is also 100.

Solution:
We have,
Effort arm = 10cm
Effort = 5N
Now, by using principle of lever
Input work = Output work
Or, Effort $\times$ effort arm = Load $\times$ load arm
Or, 5 $\times$ 10 = 50 $\times$ load arm
Or, load arm = $\frac{ 5 \times 10}{50}$
$\therefore$, The load arm is 1m.

Now,
Input work = effort arm $\times$ effort
= 10 $\times$ 5
= 50.

Output work = load arm $\times$ load
= 2 $\times$ 50
= 100.
$\therefore$, The input work is 100 and output work is also 100.

The machine which is simple in structure and makes wok easier, faster and convenient is called a simple machine.
The two examples of simple machines are nut- cracker and jack screw.

A lever is defined as a rigid bar that moves freely about a fixed point called the fulcrum.

The two examples of first class lever are beam balance and see- saw.
The two examples of second class lever are nut- cracker and paper- cutter.
Any two examples of third class lever are shovel and spade.
A pulley is a simple machine with grooved circular disc over which a rope passes.
A wheel and axle is a simple machine having two cylinders of different radius.
Any two examples of wheel and axle are screw- driver and paddle of bicycle.
Any two examples of screw are nail and driller.
A wedge is a simple machine having two or more sloping surfaces that taper either to form a sharp edge or pointed edge.

Any two examples of wedge are axe and knife.

Inclined plane is a sloping surfaces or a wooden plank which is used to push things upward.
Wheel barrow is a second class lever and beam balance is a first class lever.
Any two examples of inclined plane are staircase and ladder.
Movable pulley is a type of pulley in which pulley moves with the load.

The lever in which the effort is situated between the fulcrum and the load is called the third class lever.