newton's laws of motion_564
TRANSCRIPT
Newton’s Contributions
• Calculus
• Light is composed of
rainbow colors
• Reflecting Telescope
• Laws of Motion
• Theory of Gravitation
NEWTON’S LAWS OFMOTION.
I. Newton’s first law (law of inertia)II. Newton’s second lawIII. Newton’s third law
Newton’s Laws of Motion
1st Law – An object at rest will stay at rest,
and an object in motion will stay in motion at constant velocity, unless acted upon by an unbalanced force.
2nd Law – Rate of change of momentum=
force applied.
3rd Law – For every action there is an equal
and opposite reaction.
Newton’s First Law
(law of inertia)
An object at rest tends to stay at rest and
an object in motion tends to stay in
motion unless acted upon by an external
unbalanced force.
Balanced Force
Equal forces in opposite
directions produce no motion
Unbalanced Forces
Unequal opposing forces
produce an unbalanced force
causing motion
Concept of Inertia:
“Inertia is the inherent property of all objects that they do not change their state of rest or of uniform motion along a straight line path unless acted upon by an external force.”
1st Law of Motion:
Unless acted
upon by an
unbalanced
force, this golf
ball would sit
on the tee
forever.
Newton’s 1st Law
Because of Inertia, objects resist changes in
their motion. When the car going 80 km/hour is stopped
by the brick wall, our body keeps moving at 80 m/hour.
Newton’s First Law (law of inertia)
MASS is the measure of the amount of matter in an object.
It is measured in Kilograms
Newton’s First Law (law of inertia)
INERTIA is a property of an object that describes how much it will resist the motion of the object.
more mass means more inertia .
If objects in motion tend to stay in motion,
why don’t moving objects keep moving forever?
Things don’t keep moving forever because there’s almost always an unbalanced force
acting upon them.
A book sliding across a table slows down and stops because of the force of friction.
If you throw a ball upwards it will
eventually slow down and fall
because of the force of gravity.
There are four main types of friction: Sliding friction: ice skating
Rolling friction: bowling
Fluid friction (air or liquid): air or water resistance
Static friction: initial friction when moving an object
The unbalanced force which opposes the motion of a moving body is ,
Frictional Force :
Slide a book across a table and watch it slide to a rest position. The book comes to a rest because of the presence of a force -that force being the
force of friction- which brings the book to a rest position.
In the absence of a force of friction, the book would continue in motion with the same speed and direction - forever! (Or at least to the end of the table top.)
Newton’s Second Law
Force equals mass times acceleration.
F = ma
2nd Law
Newton’s Second Law
• WEIGHT is a measure of the
force of ________ on the
mass of an object
• measured in __________
gravity
Newtons
Newton’s Second Law
One rock weighs 5 Newtons.
The other rock weighs 0.5
Newtons. How much more
force will be required to
accelerate the first rock
at the same rate as the
second rock?
Ten times as much
2nd Law
• When mass is in kilograms and
acceleration is in m/s/s, the unit of force is
in newtons (N).
• One newton is equal to the force required
to accelerate one kilogram of mass at one
meter/second/second.
If mass remains constant, doubling the acceleration, doubles the force. If force
remains constant, doubling the mass, halves the acceleration.
Linear Momentum:
Newton’s Third Law
For every action there is an equal and
opposite reaction.
Newton’s 3rd Law• For every action there is an equal and
opposite reaction.
Book to
earth
Table to
book
3rd Law
As the birds push down
on the air with their
wings, the air pushes
their wings up and
gives them lift, thus
obeying Newton’s 3rd
law of motion.
Action: earth pulls on you
Reaction: you pull on earth
Action and Reaction on Different Masses
Consider you and the earth
Action: tire pushes on roadReaction: road pushes on tire
3rd LawThe reaction of a rocket is an application of the third law of motion. Various fuels are burned in the engine, producing hot gases.
The hot gases push against the inside tube of the rocket and escape out the bottom of the tube. As the gases move downward, the rocket moves in the opposite direction.
ReviewNewton’s First Law:
Objects in motion tend to stay in motion and objects at rest tend to stay at rest unless acted upon by an unbalanced force.
Newton’s Second Law:
Force equals mass times acceleration (F = ma).
Newton’s Third Law:
For every action there is an equal and
opposite reaction.