Forces and Motion

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Forces and Motion

• Section1.2 Speed measures how fast position
  changes.

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Vocabulary Word

• ______________ is the change of position over
  time.

Motion
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Vocabulary Word

• ____________ is a measure of how fast something
  moves or the distance it moves in a given amount
  of time.

speed
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(No Transcript)
5
0000
0001
0002
0000
0001
0002
8 meters
4 meters
0 m
How far will each skater travel in five seconds?
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Calculating Speed

• S d
• t

S speed
d distance
t time
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A racer completes a 100-meter course in 20
seconds. What is his speed?
Distance 100 m Time 20 s
What do you know?
What do you want to find out?
speed
S 100 m 20 s
Substitute into the formula
Calculate
S 5 m/s
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Practice Problem 1
A baseball travels 200 m in 25 s. What is its
speed?
S distance time
S 200 m 25 s
S 8 m/s
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Practice Problem 2
This bunny can travel 100 meters in 50 seconds.
What is his speed?
S 100 m 50 s
S 2 m/s
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Vocabulary Word

• ___________ is a speed in a specific direction.

Velocity
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If two scooters are moving at the same speed but
in opposite directions, is their velocity the
same?
5 m/s west
5 m/s east
NO! Since they have different directions they
have different velocities!
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Green arrows show velocity. A longer arrow
indicates a faster speed than does a shorter
arrow. The direction of the arrow indicates the
direction of motion.
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Vocabulary Word

• A _______________ is a quantity that has both
  size and direction.

vector
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Your dog Sam often runs away from home. You know
that he averages 2 kilometers per hour on these
adventures. Is that enough information to
determine this location when he has been gone for
20 minutes?
NO
A neighbor calls to tell you that she saw Sam
making a beeline north. Now do you have enough
information to determine his location?
YES only if he hasnt changed direction since
then.