(a) Description of the motion in words: Three cars are on a straight road. A blue car has a constant velocity of 20 m/s west; a green car remains at rest; and a red car has a constant velocity of 10 m/s east. At t = 0 the blue and green cars are side-by-side, 20 m east of the red car.
blue red
red
green
blue
(d) Equations of motion
(green) Blue car: Green car:
blue green red
Red car:
red green
blue
Figure 2.13: Multiple representations of the constant-velocity motions of three cars. These include (a) a description of the motion in words; (b) a motion diagram; (c) a diagram of the initial situation, at t = 0 (this is shown in a box); (d) equations of motion for each car; (e) graphs of the position of each car as a function of time; and (f) graphs of the velocity of each car as a function of time. Each representation gives us a different perspective on the motion.
Essential Question 2.4: Consider the graph of position-versus-time that is part of Figure 2.13. What is the significance of the points where the different lines cross? (The answer is at the top of the next page.)
Chapter 2 – Motion in One Dimension Page 2 - 9