Transcript Newton`s First and Second Laws of Motion

Newton’s First and Second
Laws of Motion
12.2
I. Scientists
Aristotle, Galileo and Newton all worked
on concepts of force and motion
 Aristotle- incorrectly proposed that force is
required to keep an object moving at
constant speed, this error held back
progress in the study of motion for almost
two thousand years.
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Galileo- helped correct misconceptions
about force and motion
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Concluded that moving objects not subjected
to friction or any other force would continue to
move indefinitely
Newton- built on the work of Galileo and
defined force and mass. He introduced his
laws of motion in Principia- his book
II. Newton’s First Law
The state of motion of an object does not
change as long as the net force acting on
the object is zero
 An object at rest remains at rest unless an
unblanced force acts on it
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ex: kicking a soccer ball
Inertia- the tendency of an object to resist
a change in motion
Upon impact, the test dummy continues
forward until it hits something – inertia
III. Newton’s Second Law
acceleration = net force = F
mass m
 The acceleration of an object is equal to
the net force acting on it divided by the
object’s mass
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
Ex: the more force you apply to throwing a
ball the more the ball accelerates
This law also works on forces in opposite
directions
Ex: seatbelts in cars- explain
pg 367 Math Practice #1-3
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IV. Weight and Mass
Weight- the force of gravity acting on an
object
Weight = mass x acceleration due to gravity
(9.8m/s2)
 mass is a measure of the inertia of an
object; weight is a measure of the force of
gravity acting on an object

Planet
Multiply your
weight by:
Mercury
0.4
Venus
0.9
Earth
1
Mars
0.17
Jupiter
2.5
Saturn
1.1
Uranus
0.8
Neptune
1.2
Moon
0.17
New weight