Transcript and the three laws of motion

SIR ISAAC NEWTON
AND THE THREE LAWS OF
MOTION
LAWS OF MOTION
ARISTOTLE (384-322 B.C.) - Greek scientist,
philosopher. Felt a force was needed to move an
object.
EX: You would have to keep a
continuous force
•
applied to a book to keep it moving
across a table.
•
“The natural state of an object was at
rest.
•The greater the force, the greater the
speed.”
•
LAWS OF MOTION
•
•
GALILEO GALILEI (1564-1642) - Italian scientist.
Concluded that it is just as natural for a body to be
in
motion with a constant speed as it is to be at rest.
NEWTON’S LAWS
ISAAC NEWTON (1642-1727) - English scientist.
Wrote famous mathematical book Principia in 1687.
This book outlined his famous Laws of Motion.
1ST LAW OF MOTION
“ Every body continues in its state of rest or
uniform speed in a straight line unless it is
compelled to change that state by a net force
acting on it.”
•
LAW OF INERTIA: The tendency of a body to
stay at rest or uniform speed.
•
2ND LAW OF MOTION
“ The acceleration of an object is directly
proportional to the net force acting on it and
inversely proportional to its mass.”
•
An object moves faster when you apply more
force to it. The bigger the object is, the harder it
is to move.
•
•
F = ma
2ND LAW OF MOTION
The bobsled accelerates because the racers are
exerting a force on the sled.
•
2ND LAW OF MOTION
FORCE
MASS x ACCELERATION
1N
1 kg
1 m/s
2N
1 kg
2 m/s
3N
1 kg
3 m/s
2ND LAW OF MOTION
FORCE
MASS
ACCELERATION
1N
1 kg
1 m/s
1N
2 kg
0.5 m/s
3RD LAW OF MOTION
“ Whenever one object exerts a force on a
second object, the second object exerts an
equal and opposite force on the first.”
•
FOR EVERY ACTION THERE IS AN EQUAL
AND OPPOSITE REACTION.
•
3RD LAW OF MOTION
•
WHAT ARE THE FORCES IN THIS PICTURE?
3RD LAW OF MOTION
•
WHAT ARE THE FORCES IN THIS PICTURE?
3RD LAW OF MOTION
•
WHAT ARE THE FORCES IN THIS PICTURE?
#1
An air hockey puck is pushed along a
frictionless surface.
The puck will continue to slide forever in
the same direction at a constant speed.
#2
You try to push Mr. Hooker; then you try to
push a chair.
Mr. Hooker will not go as far as the chair,
because he has a larger mass. According to
Newton’s 2nd Law of Motion, it takes more force
to move him.
#3
You dribble a basketball.
When you push against the basketball,
the ball pushes against your hand.
When the ball hits the floor, the floor
pushes against the ball and it bounces
back up.