The action force is the swimmer's hands and feet pushing the water backward. The reaction force is the water pushing the swimmer's hands and feet forward, propelling the swimmer through the water.

1. LAWS OF MOTION

2. GRAVITY
AND NEWTON’S
LAWS OF MOTION
By
Prof . AJALA. J
Head of Academics

3. Question????
Which object will land sooner
if dropped at the same time,
a tennis ball or a bowling ball?

4. Acceleration Due To Gravity
Objects fall to the ground at the same rate because
the acceleration due to gravity is the same for all
objects.
The mass of an object does not affect the rate at
which it falls.
Bowling ball and tennis ball

5. ACCELERATING AT A CONSTANT
RATE
All objects accelerate
toward Earth at a
rate of 9.8 m/s/s.
WHAT DOES THIS MEAN?
This means that for every second an
object falls, the object’s downward
velocity increases by 9.8 m/s.

6. Acceleration Due To Gravity
Objects fall to the ground at the same rate because
the acceleration due to gravity is the same for all
objects.
The mass of an object does not affect the rate at
which it falls.
All objects accelerate toward Earth at a rate of 9.8 m/s/s.

7. What happens when I drop a
tennis ball and a piece of
paper??
Is there something else acting on
the paper to cause it to not fall like
the tennis ball? What?

8. DOES AIR RESISTANCE
AFFECT FALLING
OBJECTS?
Yes!!
THE FORCE OF GRAVITY PULLS OBJECTS
DOWNWARD AS THE FORCE OF AIR
RESISTANCE PUSHES IT UPWARD.
FREE FALL- when an object is being pulled down by gravity,
but no other forces are acting on it.
Does free fall occur with air resistance?

9. http://www.youtube.com/watch?v=5C5_
dOEyAfk
Example of acceleration due
to gravity

10. Gravity, Free Fall, and Air Resistance
Gravity - the force that pulls objects toward
one another.
Free Fall – when only gravity is acting on an
object. This is rare because of air resistance.
All objects free fall at a rate of 9.8 m/s. A
golf ball and basketball will hit the ground
at the same time.
Air Resistance – type of fluid friction which
increases with the surface area of the object.

12. NEWTON’S FIRST LAW OF MOTION
AKA: LAW OF INERTIA
An object at rest remains at rest and an
object in motion remains in motion at constant
speed and in a straight line unless acted on by
an unbalanced force.
A golf ball on a tee.
The man will remain in motion
until a force stops his
movement.
Examples:

13. NEWTON’S FIRST LAW OF MOTION
Also called: LAW OF INERTIA
Inertia is the tendency of all objects to
resist any change in motion.

15. NEWTON’S SECOND LAW OF
MOTION
The acceleration of an object depends on the mass
of the object and amount of force applied.
FORCE=MASS X ACCELERATION
Or a=F/m
How does Newton’s
Second Law explain why
the shuttle’s acceleration
increases during takeoff?

17. • The greater mass or velocity an object has,
the greater its inertia.
• You can test this the next time you're at the grocery
store! It takes a strong push to get a loaded shopping
cart moving, but once it gathers
speed it keeps going, even if you
let go of the handle.
When you stop a moving cart full
of groceries, it takes much more
force to stop it than an empty cart.
Why? (it has more mass).

18. WHAT IS MOMENTUM?
MOMENTUM is a property of a moving object that depends on
the object’s mass and velocity.
THE MORE MOMENTUM AN OBJECT HAS, THE
HARDER IT IS TO STOP THE OBJECT OR
CHANGE ITS DIRECTION.
Momentum=mass x velocity

19. NEWTON’S THIRD LAW OF
MOTION
For every action there is an equal and
opposite reaction.
FORCES ALWAYS ACT IN PAIRS.
The action force is the swimmer’s
hand and feet pushing the water.
The reaction force is the water
pushing on the swimmer’s hands and
feet.

20. • According to Newton,
whenever objects A and B
interact with each other, they
exert forces upon each other.
• When you sit in your chair,
your body exerts a downward
force on the chair and the
chair exerts an upward force
on your body.

21. • Flying gracefully through the air, birds depend
on Newton’s third law of motion. As the birds
push down on the air with their wings, the air
pushes their wings up and gives them lift.

22. MORE EXAMPLES OF ACTION AND
REACTION FORCE PAIRS
The rabbit’s legs exert a force on
Earth. Earth exerts an equal force
on the rabbit’s legs, causing the
rabbit to accelerate upward.
The shuttle’s thrusters
push the exhaust gases
downward as the gases
push the shuttle upward
with an equal force.

24. Explain Newton’s First Law of Motion using
this picture.
A plane will not soar in the air unless it is pushed by the
exhaust from its jet engines.

25. Newton’s Second Law of Motion
- Which would you have to apply a greater
force to stop and go?
- Which would you rather buy gas for?
- Which would you rather be driving in a
head-on collision?

26. NEWTON’S THIRD LAW OF MOTION
LIST and DESCRIBE the action and reaction
forces in the following picture.