Answer:
B. Truck X was ahead, not truck Y.
Explanation:
Let's analyze the information provided.
Truck X moved from the point (0,20) to (2.8,50). This indicates that it began at the 20th kilometer and reached 50 km in 2.8 hours. Thus, its speed is v1 = (s2 - s1) / t
v1 = (50 - 20) / 2.8
v1 = 10.7 km/h
Given that it started from the 20th km, it indeed had a head start. Since the line on the graph is linear, this shows its speed was constant without any change in direction.
On the other hand, Truck Y's movement went from the origin (0,0) to (5,20), meaning it took 5 hours to travel 20 km, resulting in a speed of v2 = 20 / 5
v2 = 4 km/h
Again, the straightness of its graph line signifies it maintained a constant speed in a single direction.
Thus, it is evident that Rosa erred in her assumption that Truck Y had a head start.
