a 4-cylinder car gets 14.5km/l of gasoline from a gasoline port-type EFI system, and operates at 3000rpm (on average) at an average vehicle speed of 100kph. if the injectors gasoline flow rate (open) is 5g/sec, what is the typical injection duration (ms)? assume one injection per cylinder per cycle.

To solve this problem, we need to first understand the relationship between the various quantities given.

1. First, we need to convert the car's fuel efficiency from km/l to l/km for easier calculation. So, 1/14.5 = 0.069 l/km.

2. Next, we need to find out how much fuel the car consumes in one hour. Since the car is traveling at 100 km/h, it will consume 0.069 l/km * 100 km/h = 6.9 l/h.

3. Now, we need to convert this fuel consumption rate to g/sec, since the injector's flow rate is given in g/sec. Assuming the density of gasoline is approximately 0.74 g/ml (or 740 g/l), the car consumes 6.9 l/h * 740 g/l = 5106 g/h. To convert this to g/sec, we divide by 3600 (the number of seconds in an hour), so 5106 g/h / 3600 sec/h = 1.418 g/sec.

4. The injector's flow rate is 5 g/sec, so to find out the injection duration, we divide the car's fuel consumption rate by the injector's flow rate: 1.418 g/sec / 5 g/sec = 0.284 sec.

5. However, the question asks for the injection duration in milliseconds (ms), and there are 1000 ms in a second. So, 0.284 sec * 1000 = 284 ms.

6. But this is the total injection duration for all 4 cylinders. Since there is one injection per cylinder per cycle, we need to divide this by 4 to find the injection duration per cylinder: 284 ms / 4 = 71 ms.

So, the typical injection duration is approximately 71 milliseconds.