1. Newton’s Laws of
Motion

2. 1st
Law of Motion
 An object at rest will stay at rest and an
object in motion will stay in motion (in the
same direction and at a constant speed)
UNLESS an unbalanced force is applied.

3. Examples
 Can you explain these using the 1st
Law of
Motion?

4. 1st
Law
 More simply stated:
 If they are moving, they want to stay
moving.
 If they are still, they want to stay still.
 The only way to change what they are doing
is to apply a force.

5. Law of Inertia
 Objects are lazy – they do not want to stop
what they are doing.
 What can we call this “laziness?”
Inertia
 Inertia is a measure of it’s resistance to
change.
 The more resistant, the more inertia
 Newtons’ First Law is also called the

6. 2nd
Law of Motion
 Usually stated as an equation:
F = ma
 What does this mean?
 And don’t say force equals mass times
acceleration. Anyone can say that, but do
you really understand what it means?
 What if I restated the equation?

7. Newton’s 2nd
Law
Explained
 It means the acceleration of an object
depends on two things – the mass of the
object and the amount of force you apply
to change its motion.
 Let’s look at this relationship.

8. Let’s Look
Mathematically
 If I double the numerator, what happens?
= 4 = 8
4 4
 When one variable increases, another variable
increases the same amount.
 This is called a direct proportion
 Which 2 variables are directly proportional?

But this is science
class!

9. Math and Science
 What happens when I increase the
denominator?
 Let’s try!
4 = 4 =
4 8
 This is called an indirect proportion, or inverse
proportion
 Which 2 variables are inversely proportional?
 What does that mean?

10. Newton’s 2nd
Law
 Look at the equation. Think of the
previous fractions. Can you explain what it
means now?

11. 2nd
Law of Motion
 The greater the applied force, the faster
the object will move (acceleration).
 The more mass an object has, the more
force you need to change it’s motion

12. 3rd
Law of Motion
 For every action, there is an equal and
opposite action.

13. Let’s Review
Newton
 Once moving at a steady speed
In a straight line
It will continue moving
At a steady speed
In a straight line
 Once standing still
It will stay still

14. Newton
 It accelerates in the direction that you
push it
If you push twice as hard, it accelerates
twice as much
 If it has twice the mass
It accelerates half as much

15. Newton
 If you push on it
It pushes on you

16. Check out these videos
http://science.discovery.com/inte
http://www.fmalive.com/

17. Questions?