Newton's first law of motion states that an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. Inertia is an object's resistance to changes in its motion and is directly proportional to its mass. Applied forces can cause an object to move or stop, while frictional forces oppose motion and will eventually cause a moving object to come to rest.

1. NEWTON’S FIRST LAW OF MOTION
22 August 2022
By Thulani Innocent Nkosi

2. LESSON OBJECTIVES
At the end of the lesson you will be able to:
1. State Newton’s first law of motion.
2. Define inertia and relate it with real-life examples .
3. Explain the effect of applied force and frictional force on object.

3. SIR ISAAC NEWTON
He was an English mathematician and physicist who
is still recognized as one of the most innovative and
imaginative scientists to ever live.
He is famous for developing the law of gravity and
the laws of motion.
Well of course Newton’s First law of motion was
developed by him.
 1643-1727

5. NOW IMAGINE THIS….
CAN A ROLLING SOCCER BALL
CONTINUE ROLLING FOREVER?

6. NEWTON’S FIRST LAW OF MOTION
Newton’s first law of motion states that an object will remain stationary or
continue moving in uniform motion in a straight line unless acted upon by
an unbalanced net force (Khwanda, 2015).

7. NEWTON’S FIRST LAW OF MOTION
Let us go back to the rolling soccer ball, Newton’s first law of motion
suggests that the ball was not going to move if nobody “kicked” it (which is
applying a force to it) and the law also suggests that the ball will continue
moving with the same speed unless “something” stops it.

8. NEWTON’S FIRST LAW OF MOTION
Kicking the ball is applying a
force to it and the air or the
ground provides friction which
eventually causes an
unbalanced resultant force to
which the acceleration of the
ball will take its direction .
Eventually the ball will come
to a halt due to the air
resistance and friction on the
ground being greater than
the force applied when the
ball was kicked.
Now this “greater or less
than” is the unbalanced net
force.

9. INERTIA
The tendency of an object to remain at rest or if moving to continue
moving in a straight line is called inertia (Saboo, 2015).
Inertia is a property of an object that describes how much it will resist
change to its motion. (Jane, 2016).
According to Newton’s first law, every object has inertia that is directly
proportional to its mass.
The greater the mass of an object the harder it is to make it come to a
stop once it starts moving.
The greater the mass of an object also the harder it is to make it move if
it was not moving.

10. INERTIA:
IT WILL BE HARD TO STOP THIS MOVING TRUCK DUE TO ITS BIG
MASS.

11. INERTIA: IT WILL BE EASY TO MOVE THIS TOY TRUCK DUE TO ITS
SMALL MASS.

12. THE EFFECT OF AN APPLIED FORCE ON AN
OBJECT
An applied force is a contact
force that can be applied by an
individual or another object on an
object (Stermer, 2010).

13. THE EFFECT OF AN APPLIED FORCE ON AN
OBJECT
The applied force can cause an
object to move if pushed and it can
also cause an object to stop when
the object is being pulled while
moving in the opposite direction of
the pulling force.

14. THE EFFECT OF FRICTIONAL FORCE ON AN
OBJECT
This is the force that opposes the motion of an object which eventually
cause the object to come to rest.
When you are sliding a book on a table it will eventually come to rest
because of the presence of friction on the table which apposes the
motion of the book (Karim, 2011).

15. THE EFFECT OF FRICTIONAL FORCE ON AN
OBJECT
Look at this diagram, assume
that the friction on the book is
greater than that on the table.
The book will eventually come to
rest.

16. ANY QUESTIONS

19. REFERENCES
Jane, M. (2016). Law of Inertia. Available from SlideShare at
https://www.slideshare.net/maryjane0116/law-of-inertia-63950892
Karim, H. (2011). Sec.3&4 Newton’s Laws of Motion [1]. Available from SlideShare at
https://www.slideshare.net/Hamdy1983/sec34-newtons-lawsofmotion1
Khwanda, M. (2015). Newton’s Laws of Motion 14 April 2015. Available from SlideShare at
https://www.slideshare.net/mkhwanda1/newtons-laws-of-motion-14-april-2015-47166517
Saboo, A. (2015). Newton’s First Law of Motion [autosaved]. Available from SlideShare at
https://www.slideshare.net/anshumansaboo71/newtons-first-law-ofmotion-autosaved
Stermer, E. (2010). Newton’s Laws. Available on SlideShare at
https://www.slideshare.net/edstermer/newtons-laws-2981594