Question 1081529
Kirby moves with constant speed 5 units per hour along the line {{{y = 3x/4 +6}}} crossing
the y-axis at midnight and the x-axis later. When is the x-axis crossing made?
The x-axis is crossed when y=0.
y = 3x/4 +6 = 0
3x = -24
x = -8
The distance from (-8,0) to (0,6) = 10 units.
10/5 = 2 hours --> x-axis crossed at 0200.
---------------------
What does it mean to say that Kirby’s position is a function of time?
It varies with time.
============
What is Kirby’s position 1.5 hours after midnight?
He's 7.5 units from (0,6) on the line, and 2.5 units from (-8,0)
--> (-6,1.5)
===================
What is Kirby’s position t hours after midnight?
Since he's moving right to left (on the graph):
x(t) = -t
y(t) = -3t/4 + 6