Newton’s+laws+of+motion

1. Newton’s Laws of
Motion

2. 1
st
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 1
st
Law of
Motion?

4. 1
st
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. 2
nd
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 2
nd
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?
What does that mean?
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 2
nd
Law
Look at the equation. Think of the
previous fractions. Can you explain what it
means now?

11. 2
nd
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. 3
rd
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/interactives/literacy/newton/newton.html
http://www.fmalive.com/

17. Questions?