Question #381be

1 Answer
Aug 26, 2017

Here's what's going on here.

Explanation:

That's just the duration of the motion expressed in seconds.

"1 min = 60 s"

so

10 cancel("min") * "60 s"/(1cancel("min")) = "600 s"

Now, notice that in "600 s", the car travels a total distance of

d = v * t

d = "15 m/"cancel("s") * 600cancel("s") = "9000 m"

Assuming that this car is moving along the x axis, if you take "0 m" to be the origin of the axis, the initial position of the car will be at -"200 m" because the car is starting West of the town square and moving East, i.e. to the left of the origin and moving to the right.

The car will travel "200 m" from its initial location to the town square and "8800 m" from the town square to its new position.

"initial position " stackrel(color(white)(acolor(blue)("200 m")aaa))(->)" town square " stackrel(color(white)(acolor(blue)("8800 m")aaa))(->) " final position"

Using the x axis for help, this is equivalent to--the diagram is not to scale!

color(white)(aaaaaa)"start"color(white)(aaa)"town square"color(white)(aaaaaaaaaaa)"finish"
larrcolor(white)(aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa)/color(white)(a)rarr
color(white)(aaaa)-200color(white)(aaaaaaa)0color(white)(aaaaaaaaaaaaaaa)+8800

This is why the equation uses -"200 m" and not +"200 m" as the initial displacement of the car.