3. The term “newton” is used
in honor of Sir Isaac Newton
(1642–1727), who is the first to
explain the relationship
between force and motion. He
synthesized the work of
Galileo and other scientists into
a unifying principle that
governs the motions of
everything in the universe
These are now known as
Newton’s laws of motion.
8. WWhhaatt iiss iinneerrttiiaa??
IInneerrttiiaa iiss tthhee
tteennddeennccyy ooff aann
oobbjjeecctt ttoo rreessiisstt
cchhaannggeess iinn iittss
vveelloocciittyy::
wwhheetthheerr iinn
mmoottiioonn oorr
mmoottiioonnlleessss..
These pumpkins will not move
unless YOU MOVE IT (acted on
by an unbalanced force).
Remember: the
greater the
mass, the
harder it is to
change motion.
10. Since these two forces
are of equal magnitude
and in
opposite directions, they
balance each other. The
book is said to be in
equilibrium. There is no
unbalanced force
acting upon the book,
thus, the book maintains
its state
of motion (which is at
rest). When all the
forces acting on
an object balance each
other, the object will be
16. Upon contact, an unbalanced force
acts upon each car causing it to
abruptly stop or decelerate to rest.
Passengers wearing their seatbelts
share the same state of motion as the
car. As the car accelerates the
passengers accelerate with it. As the
cars collide and abruptly decelerate
to rest, so the passengers abruptly
decelerate to rest as well. The
wearing of the seatbelt assures that
the forces necessary for accelerated
and decelerated motion of the
passengers exist
17. What would happen if
the passengers were not
wearing their seat belts
and the car was brought
to a sudden and abrupt
halt by a collision with
another vehicle?
18. 22nndd LLaaww ::LLaaww ooff
AAcccceelleerraattiioonn
•A net force will
cause acceleration
Objects acceleration is
directly
proportional to the
net force acting on it
and inversely
proportional to the
19. Two important concepts:
MASS
•The lesser/smaller the NET FFOORRCCEE((ff)) ,, tthhee SSMMAALLLLEERR
tthhee aacccceelleerraattiioonn((aa))..
MASS
20.
21. Two important concepts:
mass
•t The bigger thhee mmaassss ((MM)),, tthhee SSLLOOWWEERR tthhee
aacccceelleerraattiioonn((aa))
MASS
26. Sample Problem 1
How much force is needed to accelerate
a 5 kg mass
at a rate of 2 m/s2?
Given
m = 5 kg
a = 2 m/s2
Solution
F = m a
= 5 kg × 2 m/s2
= 10 kg m/s2
or 10 N
30. 4. What acceleration will rreessuulltt wwhheenn aa 1122 NN nneett
ffoorrccee aapppplliieedd ttoo aa 33 kkgg oobbjjeecctt..
55.. AA nneett ffoorrccee ooff 1166 NN ccaauusseess aa mmaassss ttoo
aacccceelleerraattee aatt aa rraattee ooff 55 mm//ss22.. DDeetteerrmmiinnee tthhee
mmaassss..
66.. HHooww mmuucchh ffoorrccee iiss nneeeeddeedd ttoo aacccceelleerraattee aa 6666
kkgg sskkiieerr 11 mm//sseecc//sseecc??
77.. WWhhaatt iiss tthhee ffoorrccee oonn aa 11000000 kkgg eelleevvaattoorr tthhaatt
iiss ffaalllliinngg ffrreeeellyy aatt 99..88 mm//ss22??
88.. HHooww mmuucchh ffoorrccee iiss nneeeeddeedd ttoo aacccceelleerraattee aa
11440000 kkiillooggrraamm ccaarr 22 mmeetteerrss ppeerr sseeccoonndd//ppeerr
sseeccoonndd??
31. Newton’s 2nd Law proves that different masses
accelerate to the earth at the same rate, but with
different forces.
• We know that objects
with different masses
accelerate to the
ground at the same
rate.
• However, because of
the 2nd Law we know
that they don’t hit the
ground with the same
force.
FF == mmaa
9988 NN == 1100 kkgg xx 99..88 mm//ss//ss
FF == mmaa
99..88 NN == 11 kkgg xx 99..88
mm//ss//ss
37. 33rrdd LLaaww
Flying gracefully
through the air, birds
depend on Newton’s
third law of motion. As
the birds push down on
the air with their wings,
the air pushes their
wings up and gives
them lift.