Transcript Newton`s Laws

Newton’s Laws
Sir Isaac Newton
 Studied
physics in the late 1600’s
 Developed laws about force and
gravity
 Discovered that a prism could
separate light into the color spectrum
and vice-versa and proved that color
is a property of light
 Founded calculus
Newton’s First Law
 An
object at rest stays at rest and an
object in motion stays in motion
unless acted on by an outside
unbalanced force.
 Think
about slamming on the brakes
in the car – the car slows down, but
you don’t – locks the seatbelt.
Inertia
– the tendency of an object to
resist a change in its motion
 In order to overcome an object’s
inertia, a force must be exerted on the
object.
 Newton’s 1st Law is also called the
Law of Inertia
 Inertia

Newton's First Law of Motion
Law of Inertia

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Newton’s Second Law
 Force
equals mass x acceleration
F=ma
 Explains
how objects behave when
forces are unbalanced
Newton’s Third Law
Forces come in
pairs
 For every action,
there is a reaction

Newton’s Third Law
 Think
about
 A rocket being
launched
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Galileo
 Galileo
was a scientist who studied
math and physics in the late 1500’s
and early 1600’s in Italy
 He showed that objects with unequal
masses would fall to the ground at the
same time by doing an experiment at
the Leaning Tower of Pisa
Mass and Weight
 Mass
is the amount of matter in an
object – usually measured in g or kg
 Mass does not change with gravity
 Weight is the force of gravity on an
object – measured in N
 Weight changes with gravity, so it can
be different in different places
Calculating Weight
 Fg=weight
 Fg=mg
 This
formula is on your reference table
 The value of g is on your reference table
Calculating Weight
 An
object with a mass of 12kg on
Earth will have a mass of 12kg on the
moon. Calculate the weight of the
object on earth.
 Fg=mg
 Fg=12kg
· 9.8m/s2 = 117.6N
Calculating Weight
 An
astronaut has a mass of 90kg.
Find his weight if he is in a flight
simulator with a gravitational pull of
1.0m/s2.
 Fg=mg
 Fg=90kg
· 1.0m/s2 = 90N