WarmUp

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Warm-Up
4 minutes
Morgan is 9 years older than Emma. The sum of
their ages is 43. How old are they?
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8.5 Motion Problems

• Objectives
• To solve problems involving uniform motion

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Motion
distance rate x time
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Example 1
Bud takes a leisurely stroll He walks at a
constant rate of two miles per hour. Carrie
starts out for a brisk walk one hour later. She
walks at a constant rate of 3 miles per hour.
How long will it take for Carrie to catch up with
Bud?
d
2
t 1
d
3
t
d 2(t 1)
d 3t
2(t 1) 3t
2t 2 3t
2 t
after Carrie walks for 2 hours
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Practice
A car leaves Lompoc traveling north at 56 km/h.
Another car leaves Lompoc one hour later
traveling north on the same road at 84 km/h. How
far from Lompoc will the second car overtake the
first?
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Example 2
Kathy and Gilbert drove a total of 553 miles in
11.4 hours. Kathy drove the first part of the
trip and averaged 55 miles per hour. Gilbert
drove the second part of the trip and averaged 35
miles per hour. For what length of the time did
Kathy drive?
55
d
t
11.4 - t
553 - d
35
d 55t
20t 154
553 d 35 (11.4 t)
t 7.7
553 55t 35(11.4 t)
553 55t 399 35t
Kathy drove for 7.7 hours
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Practice
Jen and Brian drove a total of 604 miles in 12.2
hours. Jen drove the first part of the trip and
averaged 55 miles per hour. Brian drove the
second part of the trip and averaged 45 miles per
hour. For what length of the time did Jen drive?
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Homework
p.383 1,3,5