CBSE Class 6 General Knowledge

Unit 4: Science & Technology

Lesson: Simple Machines

📘 Study Module: Simple Machines

1. Introduction

Machines are tools that make our work easier. A simple machine is a basic device that helps us do work with less effort. Simple machines do not reduce work but help change the direction or amount of force applied.

2. Meaning of Simple Machines

A simple machine is a device that makes work easier by multiplying force, changing the direction of force, or increasing speed. Simple machines are commonly used in daily life.

3. Types of Simple Machines

There are six basic types of simple machines:

• Lever
• Pulley
• Wheel and Axle
• Inclined Plane
• Screw
• Wedge

Each type performs work in a different way.

4. Lever

A lever is a rigid bar that moves around a fixed point called the fulcrum. It helps lift heavy loads with less effort. Examples include seesaws and crowbars.

5. Pulley

A pulley is a wheel with a groove through which a rope passes. It helps lift heavy objects by changing the direction of force. Pulleys are used in wells and cranes.

6. Wheel and Axle

The wheel and axle consist of a wheel attached to a smaller rod called an axle. This machine helps move or lift loads easily. Examples include bicycles and door knobs.

7. Inclined Plane

An inclined plane is a sloping surface used to raise objects. It reduces the effort needed to lift heavy loads. Ramps are examples of inclined planes.

8. Screw and Wedge

A screw is an inclined plane wrapped around a rod and is used to hold things together. A wedge is used to cut or split objects. Examples include screws, knives, and axes.

9. Importance of Simple Machines

Simple machines make daily work easier and faster. They save time and effort. Many complex machines are combinations of simple machines.

📝 Questions and Answers

A. Short Answer Questions

(One sentence each)

1. What is a simple machine?
   Answer: A simple machine is a device that makes work easier.
2. Name any one simple machine.
   Answer: A lever is a simple machine.
3. What does a lever consist of?
   Answer: A lever consists of a rigid bar and a fulcrum.
4. What is a fulcrum?
   Answer: A fulcrum is the fixed point about which a lever rotates.
5. Name a simple machine used to lift buckets from a well.
   Answer: A pulley is used to lift buckets from a well.
6. What is an inclined plane?
   Answer: An inclined plane is a sloping surface used to raise objects.
7. Which simple machine is used in a bicycle?
   Answer: A wheel and axle are used in a bicycle.
8. What is a screw?
   Answer: A screw is an inclined plane wrapped around a rod.
9. What is a wedge used for?
   Answer: A wedge is used for cutting or splitting objects.
10. Why are simple machines important?
    Answer: Simple machines make work easier and save effort.

B. Long Answer Questions

(3–5 sentences each)

11. Explain what simple machines are.
    Answer: Simple machines are devices that help us do work easily. They reduce the effort needed to perform tasks. Simple machines may change the direction or amount of force. They are used in everyday life.
12. Describe a lever with an example.
    Answer: A lever is a simple machine made of a rigid bar and a fulcrum. It helps lift heavy loads with less effort. A seesaw is a common example. Crowbars also work as levers.
13. Explain the working of a pulley.
    Answer: A pulley consists of a wheel with a groove. A rope passes through the groove. It changes the direction of force. Pulleys are used to lift heavy loads.
14. Describe wheel and axle.
    Answer: The wheel and axle is a simple machine where a wheel is attached to an axle. When the wheel moves, the axle moves too. This makes lifting or moving objects easier. Examples include door knobs.
15. What is an inclined plane and how does it help?
    Answer: An inclined plane is a sloping surface. It helps lift heavy objects by reducing effort. Ramps and sloping roads are examples. It allows gradual movement upward.
16. Explain screw as a simple machine.
    Answer: A screw is an inclined plane wrapped around a rod. It is used to hold objects together. Screws convert rotational motion into linear motion. They are commonly used in furniture.
17. Describe a wedge with examples.
    Answer: A wedge is a simple machine with a sharp edge. It is used to cut or split objects. Knives and axes are examples of wedges. Wedges apply force over a small area.
18. How do simple machines save effort?
    Answer: Simple machines reduce the amount of force needed. They increase efficiency. They change the direction of force. This makes work easier and faster.
19. Give examples of simple machines used at home.
    Answer: Knives are wedges used in kitchens. Door knobs are wheel and axle machines. Bottle openers work as levers. Ramps act as inclined planes.
20. Why are simple machines important in daily life?
    Answer: Simple machines make work easier. They help lift, move, and cut objects. Many tools depend on them. Without simple machines, work would be difficult.

🧠 Multiple Choice Questions (MCQs)

(With Answers and Detailed Explanations)

1. A device that makes work easier is called a ______.
   a) tool
   b) simple machine
   c) complex machine
   d) engine
   Answer: b) simple machine
   Explanation: Simple machines reduce effort.
2. Which of the following is a lever?
   a) Ramp
   b) Seesaw
   c) Screw
   d) Wheel
   Answer: b) Seesaw
   Explanation: A seesaw works as a lever.
3. The fixed point of a lever is called ______.
   a) axle
   b) groove
   c) fulcrum
   d) wheel
   Answer: c) fulcrum
   Explanation: Fulcrum is the turning point.
4. A pulley helps by ______.
   a) increasing speed
   b) changing direction of force
   c) cutting objects
   d) joining materials
   Answer: b) changing direction of force
   Explanation: Pulley changes force direction.
5. Which simple machine is a sloping surface?
   a) Lever
   b) Wedge
   c) Inclined plane
   d) Screw
   Answer: c) Inclined plane
   Explanation: Inclined plane is sloped.
6. Which simple machine is used to cut wood?
   a) Lever
   b) Wedge
   c) Pulley
   d) Wheel
   Answer: b) Wedge
   Explanation: Wedges are used for cutting.
7. Which simple machine is used in wells?
   a) Screw
   b) Wedge
   c) Pulley
   d) Inclined plane
   Answer: c) Pulley
   Explanation: Pulleys lift buckets.
8. Wheel and axle are used in ______.
   a) knife
   b) screw
   c) bicycle
   d) ramp
   Answer: c) bicycle
   Explanation: Bicycle uses wheel and axle.
9. A screw is actually a ______.
   a) lever
   b) wedge
   c) inclined plane
   d) pulley
   Answer: c) inclined plane
   Explanation: Screw is a twisted inclined plane.
10. Which of the following is NOT a simple machine?
    a) Lever
    b) Pulley
    c) Engine
    d) Wedge
    Answer: c) Engine
    Explanation: Engine is a complex machine.
11. A knife is an example of ______.
    a) pulley
    b) wedge
    c) lever
    d) wheel
    Answer: b) wedge
    Explanation: Knife cuts using wedge shape.
12. Which simple machine is used to tighten bolts?
    a) Screw
    b) Lever
    c) Pulley
    d) Inclined plane
    Answer: a) Screw
    Explanation: Screws hold objects together.
13. Which simple machine changes rotational motion into linear motion?
    a) Lever
    b) Pulley
    c) Screw
    d) Wedge
    Answer: c) Screw
    Explanation: Screws convert motion.
14. Which machine helps lift heavy loads easily?
    a) Wheel
    b) Pulley
    c) Wedge
    d) Knife
    Answer: b) Pulley
    Explanation: Pulley reduces effort.
15. Door knobs work on the principle of ______.
    a) lever
    b) pulley
    c) wheel and axle
    d) wedge
    Answer: c) wheel and axle
    Explanation: Knobs use wheel and axle.
16. Which machine spreads force over a small area?
    a) Wedge
    b) Pulley
    c) Lever
    d) Wheel
    Answer: a) Wedge
    Explanation: Wedges concentrate force.
17. Simple machines help us to ______.
    a) increase work
    b) waste energy
    c) reduce effort
    d) stop motion
    Answer: c) reduce effort
    Explanation: They make work easier.
18. Which simple machine is a ramp?
    a) Screw
    b) Wedge
    c) Inclined plane
    d) Lever
    Answer: c) Inclined plane
    Explanation: Ramp is an inclined plane.
19. Which of the following is a complex machine?
    a) Bicycle
    b) Knife
    c) Pulley
    d) Ramp
    Answer: a) Bicycle
    Explanation: Bicycle uses multiple simple machines.
20. Simple machines are important because they ______.
    a) make work harder
    b) save time and effort
    c) stop movement
    d) increase weight
    Answer: b) save time and effort
    Explanation: They reduce effort and time.

✅ End of Lesson

Prepared strictly in accordance with the NCERT syllabus and CBSE Class 6 examination standards.