Answer:
Step-by-step explanation:
A) What is the speed of the pedestrian BC, CD, and DE?
Speed from B to C = distance/time = (40 - 20) / 4 = 20/4
= 5 km/h
Speed from C to D = distance/time = 0 / 2
= 0 km/h
Speed from D to E = distance/time = (20 - 0) / (10 - 6) = 20/4
= 5 km/h
B) After what time since the stop did he arrive at point E?
Since the stop at D, he arrived at E after (10 - 6) = 4 h
C) Write the formulas for function d(t) for sections BC, CD, and DE
For BC, d = 40 when t = 0 and d = 20 when t = 4
So d(t) = 40 - 5t
For CD, d = 20 when t = 4 and t = 6
So d(t) = 20
For DE, d = 20 when t = 6 and d = 0 when t = 10
So d(t) = 5 * (10 - t) or d(t) = 50 - 5t
