Class-8-PHYSICS-Ch-1-Force-and-Pressure-Session-1.ppsx

Ch 1

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CLASS VIII PHYSICS
CHAPTER 1
FORCE AND PRESSURE
SESSION 8.1.1

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TOPICS TO BE COVERED IN THIS
SESSION:
1.WHAT IS FORCE ?
2.HOW AND WHEN ARE WE
USING IT ?
3.WHAT ARE DIFFERENT
TYPES OF FORCES ?
4.IS INTERACTION NECESSARY
FOR FORCE ?

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What is Force?
Force is something we use in
our daily life, to make things
move, to change the
direction/speed of moving
objects or even to change the
shape of any object.
Now the question arises why
do we need force?

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Now let us observe a few examples of pull and push…
PUSH PULL

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So by now you can easily understand the need of force in our
daily life.
If there were no force, our day-to-day activities would not be
possible. We need force to perform various activities.
If there is no force, we may look like “Mr. Tired”.
“ I can’t do anything, I am
exhausted with no energy left…..”

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As you all have seen in the previous slides that force (either a
Pull or Push) needs two bodies to interact with each other.
So we can conclude that for a force to come into play, at least
two or more bodies must interact with each other. If they don’t
do so, a force can’t be exerted.
INTERACTING BODY NON-INTERACTING BODY

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Can you identify which ones of these are contact and non-contact
forces?
Do objects feel force even if they are not interacting directly ?
Now let’s find out the types of Forces that we know about:
1. Muscular Force: Force due to elongation and contraction
of Muscles.
2. Magnetic Force: The attraction or repulsion of object by
magnets.
3. Frictional Force: The force which opposes the motion of
any object.
4. Nuclear Force: The force which binds the sub-atomic
particles.
5.Gravitational Force: The force of attraction between all
the particles in universe.
6. Electrostatic Force: The force between two charged
objects.
We will learn
more about this in
the next session.

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PRACTICE TASK
(To be done in the notebook)
Q1. Define Force.
Q2. Is it possible for a force to come into play when two bodies are not interacting
with each other?
Q3. What is the effect of application of force on a moving body?
Q4. Why does a cricket ball fly off after being hit by a cricket bat?

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That’s All For Today
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https://youtu.be/wtyDFM3lEJU
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STAY HOME… STAY SAFE… STAY HEALTHY….
SEE YOU ALL SOON!!

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