# Concept Map

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# Textbook

## Useful websites

1. This is a college lecture by Prof Walter Levin explaining gravitation. Click here to see the video.

2. Conceptual Physics
3. Physics Classroom

## Reference Books

The following textbooks are good references

1. Conceptual Physics, Paul Hewitt, 10th Edition
2. Physics for Scientists and Engineers, Douglas C. Giancoli, 3rd Edition
3. Resnick & Halliday with Jearl Walker, 8th Edition
4. NCERT Class 9 textbook Motion
5. NCERT Class 9 textbook Laws of Motion
6. NCERT Class 9 textbook Gravitation

## An image of a concept map for gravitation

This is an image of a mind map developed by Shri Chaluvanarayanaswamy # Teaching Outlines

1. Contact and Non-Contact Forces
2. Understanding Contact Forces
3. Gravitation acts at a distance

.

## Concept #1 - Contact and Non-Contact Forces

### Learning objectives

1. Forces can act in contact
2. Forces can act over a distance

### Notes for teachers

These are short notes that the teacher wants to share about the concept, any locally relevant information, specific instructions on what kind of methodology used and common misconceptions/mistakes.

Forces can act at a distance and are called non-contact forces. To understand gravitation, we need to understand inertial and gravitational properties of mass. Gravity is one of the four fundamental forces. This document further discusses the concept of acceleration due to gravity and gravitational potential energy. Gravity is responsible for planetary motion and introduces the Kepler's laws of planetary motion.

In everyday life, gravitation is most familiar as the cause due to which masses fall to the ground. Gravitation causes dispersed matter to coalesce, and coalesced matter to remain intact, thus accounting for the existence of the Earth, the Sun, and most of the macroscopic objects in the universe. Gravitation is responsible for keeping the Earth and the other planets in their orbits around the Sun; for keeping the Moon in its orbit around the Earth; for the formation of tides; for natural convection, by which fluid flow occurs under the influence of a density gradient and gravity; for heating the interiors of forming stars and planets to very high temperatures; and for various other phenomena observed on Earth and the Universe. These are some of the questions we will explore here.

### Activity No # 1 - The various forces we see

• Estimated Time- 30 minutes
• Materials/ Resources needed - Discussions
• Prerequisites/Instructions, if any
• Multimedia resources

The following pictures have been sourced from the NCERT Class 7 textbook.

• Process (How to do the activity)
1. This is in the form of a discussion
2. Students explore words like force, push, pull, contact, distance, etc
3. Let the students look at the picture and describe the force and the effect
• Developmental Questions (What discussion questions)
1. What do we mean when we say force?
2. What does it do? (Produces an acceleration/ change in state - they can start with push and pull)
3. For force to be there, do I have to touch? (Contact)
4. When have you seen non-contact forces? (Electric shock, magnetism)
5. Force can act at a distance; it is called field
• Evaluation (Questions for assessment of the child)
1. How will you define the field of a force?
2. Does the field have a definite size?
• Question Corner

### Activity No # 2 More about contact forces

• Estimated Time- 30 minutes
• Materials/ Resources needed - Discussions
• Prerequisites/Instructions, if any

Students must have been introduced to the Newton's laws.

• Multimedia resources
• Process (How to do the activity)
1. This is in the nature of discussions
2. Present scenarios for children to analyse
• Developmental Questions (What discussion questions)
1. When you hang a bucket from a rope what are the forces acting? (Tension force is the force that is transmitted through a string, rope, cable or wire when it is pulled tight by forces from opposite ends. The tension force is directed along the length of the wire and pulls equally on the objects on the opposite ends of the wire.)
2. In which direction does tension act?
3. Is this the same as friction? When do you notice friction? (Frictional force is the force exerted by a surface as an object moves across it or makes an effort to move across it. When two objects are in contact but are not moving relative to one another then the frictional force between the two surfaces is called static friction. When the two objects are moving relative to one another, the friction between the surfaces is called the kinetic friction.)
4. When you push against an object, any surface, what do you feel? Do you feel a push back? Normal force is the perpendicular force that is exerted upon an object that is in contact with another stable object. If a book is resting upon a surface, then the surface is exerting an upward force upon the book in order to support the weight of the book. A normal force can also be exerted horizontally. If a person leans against a wall, the wall pushes back on the person.
• Evaluation (Questions for assessment of the child)

1. What do the moving green and yellow circles indicate?
2. When you are rubbing the yellow book on the green book what happens? How do you know that the heat is being generated?
3. When the temperature goes very high, the yellow circles fly off. What does this mean physically?
4. Is there any force acting in this picture between the books?
5. Is gravitational force acting?
• Question Corner

## Concept #2 - Gravitation acts at a distance

### Learning objectives

1. Gravitation is a field force
2. It is very significant in explaining many events that we see

### Notes for teachers

These are short notes that the teacher wants to share about the concept, any locally relevant information, specific instructions on what kind of methodology used and common misconceptions/mistakes. Gravitation explains several phenomena

1. the force that allows us to move on Earth
2. the motion of the moon around the Earth
3. the motion of the planets around the Sun
4. the tides due to the moon and the sun

### Activity No # 1 - See gravity in action

• Estimated Time - 30 minutes
• Materials/ Resources needed - Projector
• Prerequisites/Instructions, if any
• Multimedia resources
 Image: Look at this animation here Image: Look at the picture of a pendulum here
• Process (How to do the activity)
1. Show the multimedia resources
2. Generate a mind map on what students understand about gravitation
• Developmental Questions (What discussion questions)
1. What causes the small sphere to move towards the larger one?
2. Is there a force?
3. What is the nature of that force?
4. In a pendulum what is the force acting?
• Evaluation (Questions for assessment of the child)
1. Can you state the force you have observed as a law?
2. What are the various factors it depends on?
• Question Corner
1. How do we walk?

### Activity No #

• Estimated Time
• Materials/ Resources needed
• Prerequisites/Instructions, if any
• Multimedia resources