class 9 Chapter-6 (physics)
In Chapter 4, you learnt to describe the motion of an object in terms
of its position, velocity and acceleration. But you did not consider
what causes motion. Is there an underlying cause for a change in
position and velocity of an object? What is the nature of this cause?
Do all motions require a cause? In this chapter, we will investigate
what causes changes in the motion of objects. We will also discuss
Newton’s three laws of motion and learn how to apply them.
6.1 The Concept of Force
Grade 8
Curiosity
Chapter 5
You may recall learning earlier that a force can make an
object move from rest, change the speed and direction
of motion of a moving object, and can even change the
shape of an object. For example, a ball at rest starts moving when
you apply a force, a force applied by a cricket bat on a cricket ball
changes its direction, and a lemon can be squeezed by the force
applied by your fingers.