1. The problem statement, all variables and given/known data Garbage Trucks, one after the other, are heading for the dump. They move at 19.7 m/s, and every 3 min, 2 of them arrive at the dump. A cyclist, moves at 4.47 m/s, heading for the dump as well. a) With what frequency do the trucks overtake the cyclist? b) What if there was a hill, that didn't phaze the trucks, but resulted in the cyclist going at 1.56 m/s. What's the frequency now? 2. Relevant equations v = Δx/Δt 3. The attempt at a solution Well, first of, I decided to find the distance from the starting point of the trucks to the dump. vt = Δx/Δt <=> Δx = 19.7 m/s * 180 s = 3546 m Using that, I found the time the cyclist needs to cover the same distance. vc = Δx/Δt <=> Δt = 3546 m / 4.47 m/s = 793.3 s = 13.22 min Then I figured that I'd say: -The cyclist needs 13.22 minutes to reach the end. -2 trucks need 3 minutes to reach the end. -So, how many times do the trucks cover that distance in the time the cyclist does? -So: N = 13.22 /3 = 4.41 times Now, we have that: In 13.22 minutes, 2 trucks overtake the cyclist, 4.41 times, therefore, 8.82 trucks overtake the cyclist in that timespan. In one minute, how many trucks overtake him? f = 8.82/13.22 = 0.667 And that's where I get stuck, because the book's answer is: 0.515 Obviously I'm missing something, but I just can't figure out what. As for (b), I'm not sure if the whole drive is a hill, or if it's just a small hill. But it doesn't specify any points or whatnot, so I assume it's the former (trucks keep the same speed all the time, but the cyclist changes his, and it's basically (a) with different numbers). Any help is appreciated!