Aryan: simple machine

Chapter 11 – Simple Machines

Welcome to Simple Machines!
In this chapter, we learn about simple machines, their types, uses and examples. These answers are written in easy and simple English.

1. Let's Do

Name the simple machines used for doing the following activities.

1. Cutting a cloth – Scissors
2. Fetching water using a bucket – Pulley
3. Opening a bottle – Bottle opener
4. Opening a door using a doorknob – Wheel and axle
5. Cutting vegetables – Wedge (Knife)
6. Cracking a nut – Nutcracker

A. Tick (✓) the Correct Option

1. The machines having few or no moving parts are called:
(i) Complex machine
(ii) Simple machine ✓
(iii) Combination machine

2. ______ is not an example of wedge.
(i) Knife
(ii) Axe
(iii) Broom ✓

3. ______ is not an example of class I lever.
(i) Scissors
(ii) Pliers
(iii) Stapler ✓

4. An example of class II lever is:
(i) Wheelbarrow ✓
(ii) Scissors
(iii) Claw hammer

5. A simple machine that is used to hold things together firmly:
(i) Wedge
(ii) Screw ✓
(iii) Pulley

B. Write T for True and F for False

Questions	Answer
1. Inclined plane, screw and wedge are examples of complex machines.	False (F)
2. A wedge is a simple machine used to push objects.	False (F)
3. A pair of tweezers is an example of class I lever.	False (F)
4. A fishing rod is an example of class III lever.	True (T)
5. A screw looks like a nail with grooves cut into it.	True (T)

C. Give Two Examples of Each

Simple Machines	Examples
1. Simple machines	Scissors, Screwdriver
2. Class I lever	Scissors, Seesaw
3. Inclined plane	Ramp, Slide
4. Wedge	Knife, Axe
5. Class II lever	Wheelbarrow, Nutcracker
6. Class III lever	Fishing rod, Tweezers

D. Match the Following

Column A	Correct Answer
1. Pulley	iii. Rope around a wheel
2. Wedge	v. Used to split objects
3. Wheel and axle	i. Wheel rotates around the centre
4. Class I lever	ii. Fulcrum is between load and effort
5. Class III lever	iv. Effort is between load and fulcrum

E. Write One Word for the Following

1. A tool that makes our work easy:
Machine

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2. A tilted plane used to move a heavy object:
Inclined plane

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3. A fixed point around which a rod moves:
Fulcrum

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4. A machine that has one broad and one sharp or pointed end:
Wedge

F. Define the Following Questions

1. What are simple machines? Give three examples.

Simple machines are tools that make our work easier and faster. They have few or no moving parts. Examples: Scissors, bottle opener and screwdriver.

2. What is a lever? Explain different types of levers with examples.

A lever is a straight, rigid bar that moves around a fixed point called the fulcrum. It helps us lift or move heavy objects with less effort. There are three types of levers:

1. Class I Lever
In a class I lever, the fulcrum lies between the load and the effort. Examples: Scissors, seesaw, claw hammer and pliers.

2. Class II Lever
In a class II lever, the load lies between the fulcrum and the effort. Examples: Wheelbarrow, nutcracker and bottle opener.

3. Class III Lever
In a class III lever, the effort lies between the fulcrum and the load. Examples: Fishing rod, tweezers, shovel and tongs.

3. What is a pulley? Explain different types of pulleys with examples.

A pulley is a simple machine used to lift heavy objects. It consists of a small wheel with a groove around its edge and a rope or chain.

There are two types of pulleys:

1. Fixed Pulley: It has a fixed axle. It makes work easier by changing the direction of force. Example: A pulley used in a well to draw water.

2. Movable Pulley: In this pulley, the load is attached to the pulley. It helps us lift heavy objects with less effort. Example: Movable pulleys used in cranes.

4. What is a wedge and how does it work?

A wedge is a simple machine made up of two inclined planes. It has one sharp edge and one blunt edge. It is used for cutting or splitting objects. Examples: Knife, axe, needle and fork.

5. Name the simple machines associated with the following:

Objects	Simple Machine
(i) Axe	Wedge
(ii) Nail cutter	Lever
(iii) Stapler	Lever
(iv) Sugar tongs	Class III lever

6. Write a few lines about screw.

A screw is a simple machine that looks like a nail with grooves cut into it. It is an inclined plane wrapped around a cylinder. The grooves are called threads. A screw is used to hold things together firmly. Examples: Wood screw, bolt and screw jack.

Picture Study

Identify the type of lever in the following objects.

1. Fishing Rod: Class III Lever

2. Scissors: Class I Lever

3. Bottle Opener: Class II Lever

Quick Revision

Simple Machine	Main Use
Lever	To lift or move objects
Pulley	To lift heavy objects
Inclined Plane	To move objects up or down
Wedge	To cut or split objects
Screw	To hold things together firmly
Wheel and Axle	To make movement easier

Remember:
There are six types of simple machines:

1. Lever
2. Pulley
3. Inclined Plane
4. Wedge
5. Screw
6. Wheel and Axle

Thank You!
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