Class 9 Science — Chapter 8: FORCE AND LAWS OF MOTION

What you'll learn

• ▸Concept of Force and its Effects
• ▸Balanced and Unbalanced Forces
• ▸Galileo's Contribution to the Concept of Motion
• ▸Newton's First Law of Motion
• ▸Inertia
• ▸Everyday Examples of Inertia

Chapter Summary

--- PAGE 1 --- Chapter 8 FORCE AND LAWS OF MOTION 0964CH09 In the previous chapter, we described the motion of an object along a straight line in terms of its position, velocity and acceleration. We saw that such a motion can be uniform or non-uniform. We have not yet discovered what causes the motion. Why does the speed of an object change with time? Do all motions require a cause? If so, what is the nature of this cause? In this chapter we shall make an attempt to quench all such curiosities. For many centuries, the problem of motion and its causes had puzzled scientists and philosophers. A ball on the ground, when given a small hit, does not move forever. Such observations suggest that rest is the “natural state” of an object. This remained the belief until Galileo Galilei and Isaac Newton developed an entirely different approach to understand motion. In our everyday life we observe that some effort is required to put a stationary object into motion or to stop a moving object. W…

Practice Questions from this Chapter

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1. Explain unbalanced forces simply. Get Solution →
2. Describe inertia with an example. Get Solution →
3. Give an example of inertia. Get Solution →
4. According to the chapter, the concept of force is based on what common actions? Get Solution →
5. What is the name given to the tendency of undisturbed objects to stay at rest or keep moving with the same velocity? Get Solution →
6. Newton's first law of motion is also known by what other name? Get Solution →
7. Which of the following is NOT an effect of force mentioned in the text? Get Solution →
8. What happens if a block is pulled from both sides with equal forces? Get Solution →

Did you know?

• 💡 Gravity is the weakest of the four fundamental forces in the universe.
• 💡 A spaceship launched into deep space will travel forever without stopping.
• 💡 It takes less force to push a car on the Moon than on Earth.
• 💡 Sir Isaac Newton supposedly developed his ideas after seeing an apple fall.
• 💡 An ant can lift items 50 times its own weight using sheer muscle force.

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