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ACCELERATION
Acceleration
is a change in the
velocity of an object. That me
ans that
the object could be speeding u
p,
slowing down, or changing di
rection
and it would be accelerating. T
he time
it takes for a car to go from 0 to 6
0
miles per hour is a common m
easure
of a car’s ability to accelerate
.
FORCE
When a car turns a corner sharp
ly,
accelerates, or decelerates, you f
eel a push
or a pull on your body. This is b
ecause the
car is exerting a force on you. A f
orce is
necessary to make an object m
ove and is
proportional to the amount of m
ass and
the acceleration of an object. It i
s very
important for the engineers w
ho design
cars to understand the forces t
hat a car
experiences when in motion. B
ased on your
experiences, what forces do y
ou think act
on a car when it is moving?
WORK
The way that physicists defi
ne work is different than the
common usage of the word
. Work is when a force
causes a displacement in th
e same direction as the
motion of an object. For exa
mple, if you were walking
around at a steady velocity w
ith a box in your arms you
would not be performing w
ork. This is because the forc
e
required to hold up the box p
oints in the upward
direction, while the displac
ement from your walking
around is in the horizontal d
irection. However, if you
were to push a box along th
e floor or lift a box up, you
would be performing work.
14
The Physics of Cars