A railroad train travels forward along a straight track at 80.0 m/s for 1 000 m and then travels at 50.0 m/s for the next 1 000 m.What is the average velocity?
A)65.0 m/s
B)61.5 m/s
C)63.7 m/s
D)70.0 m/s

Question

Quizplus · Accepted Answer

We can use the formula for average velocity:

average velocity = total displacement / total time

The total displacement is the sum of the two distances traveled:

total displacement = 1000 m + 1000 m = 2000 m

The total time is the sum of the times traveled at each speed:

total time = (1000 m) / (80.0 m/s) + (1000 m) / (50.0 m/s) 
total time = 12.5 s + 20 s = 32.5 s

Plugging in these values, we get:

average velocity = 2000 m / 32.5 s 
average velocity = 61.5 m/s

Therefore, the best choice is B.

A Railroad Train Travels Forward Along a Straight Track at 80.0