Session 4: Speeds, Rates, Steepness, and Lines (45 minutes) In
Parts B and C we examined the proportionality of mixtures and
scale models. In this activity, we will take a close look at
graphs to learn more about the relationships between distance
and time, and between steepness and speed. Note 8 Suppose seven
cars are all near an intersection. The graph below show the
distances between cars and the intersection as time passes.
Study this graph carefully and then try to answer the following
questions. In what direction is each car moving in relation to
the intersection? Compare the cars' speeds. How do their speeds
relate to the steepness of the lines? How could you approximate
the cars' speeds using the labels on the axes? Close Tip Does
the distance vary directly with time for any of the cars? That
is, is the relationship between distance and time proportional
for any of the cars? How do you know? Do any of the cars stop
during their trips? If so, which cars? Choose one of the seven
cars, and describe your