Unformatted text preview: Motion, Acceleration and Forces
Eric Richardson, M.D.
Cheongshim International Academy S1 Describing Motion Motion How would you describe the motion of
How
people and things around you?
people
It’s an age old problem Describing motion Aristotle’s notions of
Aristotle’s
motions (384322)
motions Natural motion Forced motion Voluntary All motion is in a
All
straight line
straight Except heavenly
Except
motion
motion Aristotelian motion: http://library.thinkquest.org/11924/aristotle.html Describing motion Aristotle’s notions of motions (384322) Natural motion Forced motion Voluntary All motion is in a straight line Except heavenly motion Aristotelian motion: Describing motion Describing motion Galileo Progress of practical
Progress
experience:
experience: Art: More careful
Art:
observation and
perspective
perspective Use of cannons in
Use
warfare
warfare Why? Describing motion Galileo Developed the concept of
Developed
inertia
inertia Showed that a ball moving
Showed
as in this experiment
follows a curved motion
follows Aristotelian motion: http://library.thinkquest.org/11924/aristotle.html Galileo Known as the father of
Known
astronomy, but also like the
father of science
father Utilized scientific method: Careful observation Careful notekeeping
Careful
and measurement
and Making hypotheses Predicting and repeated
Predicting
testing
testing Verifiable results Describing motion Isaac Newton Careful observation and records keeping Developed concept of inertia into the First
Developed
Law of motion “An object at rest tends to stay at rest
An
and an object in motion tends to stay in
motion unless acted on by an outside
force.”
force.” Famous mathematical formula of the 2nd
Famous
law gave changes in motion a firm
mathematical basis.
mathematical F=ma Aristotelian motion: http://library.thinkquest.org/11924/aristotle.html S1 Describing Motion Motion How would you describe the motion of
How
people and things around you?
people
1.
Motion is a change in position
• So you don’t need to see it move,
So
if the position changes in relation
to other things around it.
to S1 Describing Motion Motion How would you describe the motion of
How
people and things around you?
people
1.
Motion is a change in position
2.
Position depends on a reference frame.
• So, how you describe where something
So,
is depends on what things you define
as being near it.
as S1 Describing Motion • Motion How would you describe the motion of
How
people and things around you?
people
1.
Motion is a change in position
2.
Position depends on a reference frame.
3.
Motion is relative.
So, without these elements in our description, it
So,
is difficult to describe motion.
is S1 Describing Motion Distance vs Displacement The total distance travelled
The
is sometimes very different
from how far you end up
from the starting point.
from The distance from the
The
original starting point is
the displacement
the Displacement includes
Displacement
measurement of length and
has a direction, therefore
it’s a…?
it’s S1 Describing Motion
SPEED
“I feel the need… the need… for SPEED!”
Tom Cruise in Top Gun QuickTimeª and a
TIFF (LZW) decompressor
are needed to see this picture. S1 Describing Motion Speed The distance an object
The
travels per unit time
travels
Instantaneous speed What you would see on
What
your speedometer in the
car
car S1 Describing Motion Average speed Describes how fast the
Describes
object moved over the
entire distance it traveled.
entire It is equal to the total
It
distance traveled divided
by the total time it took to
get there.
get S1 Describing Motion d
v= t S1 Describing Motion
d
v= t
Problem 1: An elevator travels a distance of 220 m
from the first floor to the 60th floor in 27.5 seconds.
What is the elevator’s average speed?
Problem 2: A motorcyclist travels with an average
speed of 20 km/h. If the cyclist is going to a friend’s
house 5 km away, how long does it take the cyclist to
make the trip? S1 Describing Motion Velocity Speed and
Speed
Direction VECTOR
Direction Both escalators are
Both
going the same
speed but the
direction is
different
different S1 Describing Motion Velocity Speed and
Speed
Direction
VECTOR
VECTOR Earth goes
Earth
around the sun in
a nearly constant
speed
speed What about the
What
velocity?
velocity? ...
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 Spring '11
 fds
 Scalar, Velocity, Galileo

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