Transcript Motion - Marion ISD

http://commons.wikimedia.org/wiki/File:Soccer_kick.jpg
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Changes in motion can be measured
and graphically represented.
Forces cause changes in position,
speed, and direction.
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Motion is a change in position, which is
measured by distance and time.
Anything moving is in motion.
http://commons.wikimedia.org/wiki/File:Mercedes_In_Motion.jpg
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A force is a push or pull that can
change motion.
A force can move an object.
 A force can transfer energy to an object.
 For example, pushing on a wall doesn’t move
the wall, but energy is being transferred.
 Force = mass x acceleration
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In order for a force to move
an object, there must be
unbalanced forces.
Like tug of war…the winners
are pulling the other team
with more force; therefore,
the pulling forces are
unbalanced.
http://commons.wikimedia.org/
wiki/File:Tug_of_war_2.jpg
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Unbalanced forces can change the
position, speed, or direction of an object.
Resistance forces (friction or wind) that
oppose motion can slow down an object.
A force in the same direction can cause an
object to speed up.
A force from a different direction can
change the object’s direction.
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If we have unbalanced forces, then
there must be balanced forces.
When forces are balanced, an
object’s motion will be constant. It
will not change speed or direction.
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We talk about speed everyday.
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Speed is the distance traveled by a moving
object per unit of time.
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Speed affects the energy of an object. The
faster it moves, the more kinetic energy it
has.
Speed = distance
time
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The energy of motion
Objects in motion have kinetic energy.
Speed and mass affect the kinetic
energy of an object.
If two objects are moving at the same
speed, but one object has a greater
mass—then the object with the greater
mass will have more kinetic energy.
The more mass in an object, the more
force needed to move it.
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If I traveled 30 meters in 10 seconds,
what was my speed?
S = D/T
o 30m/10s
o 3 m/s
o
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Distance is a description of how far
an object traveled between two
points.
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Velocity and speed are like fraternal twinsvery similar, but with important
differences.
Velocity is speed in a given direction.
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35 mph NORTH
4 km/sec EAST
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100 m/s right
1500 km/s
65 m/s north
3000 km/s
Velocity
Speed
Velocity
Speed
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Acceleration is a change in the rate of
speed.
It can be a change in speed, direction,
or both.
Acceleration = Change in speed (m/s)
Time (s)
Example: 0 to 60mph in 3s
The race car accelerated from stop to 60 m/s
by the finish line.
It took the race car 8.0 seconds to finish.
What was the acceleration?
Original speed = 0
Final speed = 60 m/s
Time = 8.0 seconds
Acceleration = 60 - 0m/s = 7.5 m/s2
8.0s
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Friction is a force that opposes motion.
It can be caused by wind, water, surface
texture, etc.
Have you ever ridden down the street on
your bike and felt the wind push against
you?
That’s air resistance!
Air resistance is the frictional force from
the air that resists forward motion.