4. • Newton’s laws of motion
are three physical laws that establish the science of
kinematics. These laws describe the relationship
between the motion of an object and the force acting
on it. They are essential because they are the
foundation of classical mechanics, one of the main
branches of physics.
It was Isaac Newton who
established these laws, and he
used these laws to explain many
physical systems and phenomena.
5.
6. Newton's first law of motion
is often stated as:
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.
7. Newton’s first law talks about the tendency of a
body to remain in its present state in motion.
There are two states of motion that are
mentioned in the first law – one which predicts
the behaviour of stationary objects and the other
which predicts the behaviour of moving objects.
8. Two Clauses
• one that predicts the
behaviour of stationary
objects
• and the other that predicts
the behaviour of moving
objects
9. The behavior of all objects can be described by saying
that objects tend to "keep on doing what they're
doing" (unless acted upon by an unbalanced force).
If at rest, they will continue in
this same state of rest. If in
motion with an eastward
velocity of 5 m/s, they will
continue in this same state of
motion (5 m/s, East).
10. If in motion with a leftward velocity of 2 m/s, they will
continue in this same state of motion (2 m/s, left). The
state of motion of an object is maintained as long as
the object is not acted upon by an unbalanced force.
All objects resist changes in
their state of motion - they tend
to "keep on doing what they're
doing."
11. Galileo refined the
concept of inertia....
The theory of inertia says
that the inertia of an
object will maintain its
state of motion.
12. Galileo's law of inertia states:
If a body going up moves slower
and slower, and a body going down
goes faster and faster, a body that
neither going up nor going down
goes neither slower nor faster; it
goes with a constant speed along
the same straight line.
13. Blood rushes from your head to your
feet while quickly stopping when
riding on a descending elevator.
EXPLANATION:
Blood rushes from your head to your
feet while quickly stopping when riding
on a descending elevator. Your blood's
inertia (resistance to changes in motion)
causes it to continue moving downward
while you're stopping, so it rushes from
your head to your feet.
14. The head of a hammer can be tightened
onto the wooden handle by banging the
bottom of the handle against a hard
surface.
EXPLANATION:
The head of a hammer can be tightened
onto the wooden handle by banging the
bottom of the handle against a hard surface.
... This means that it resists the change in
motion more, so it continues moving downward
after the handle stops, thus tightening the
head of the hammer.
15. A brick is painlessly broken over
the hand of a physics teacher by
slamming it with a hammer.
(CAUTION: do not attempt this at
home!)
EXPLANATION:
The physics behind it is inertia. It
takes more force to move a large
mass than it takes to move a small
mass. The hammer it moving at a
high rate of speed and when it
strikes the brick with a large force,
the mass of the brick is larger and
16. To dislodge ketchup from the bottom
of a ketchup bottle, it is often turned
upside down and thrusted downward
at high speeds and then abruptly
halted.
EXPLANATION:
To dislodge ketchup from the bottom
of a ketchup bottle, it is often turned
upside down and thrust downward at
high speeds and then abruptly halted.
The inertia of the ketchup causes it to
continue moving downward after the
bottle is halted. This means that the
17. Headrests are placed in cars to
prevent whiplash injuries during rear-
end collisions.
EXPLANATION:
Headrests are placed in cars to prevent
whiplash injuries during rear-end
collisions. The inertia of your head
causes it to continue moving
forward at the same speed (constant
velocity – resistance to change in
motion) even though the car is
accelerating forward because of the
18. While riding a skateboard (or wagon
or bicycle), you fly forward off the
board when hitting a curb or rock or
other object that abruptly halts the
motion of the skateboard.
EXPLANATION:
While riding a skateboard (or wagon or
bicycle), you fly forward off the board when
hitting a curb or rock or another object that
abruptly halts the motion of the skateboard.
Both you and the skateboard are moving
along; but when the skateboard stops, your
inertia continues to carry you forward.
