Читать книгу Physics I For Dummies - Steven Holzner - Страница 70

Given a constant acceleration and the change in velocity, you can figure out both time and distance. For instance, imagine you’re a drag racer. Your acceleration is 26.6 meters per second², and your final speed is 146.3 meters per second. Now find the total distance traveled. Got you, huh? “Not at all,” you say, supremely confident. “Just let me get my calculator.”

You know the acceleration and the final speed, and you want to know the total distance required to get to that speed. This problem looks like a puzzler because the equations in this chapter have involved time up to this point. But if you need the time, you can always solve for it. You know the final speed, v_f, and the initial speed, v_i (which is zero), and you know the acceleration, a. Because , you know that

Now you have the time. You still need the distance, and you can get it this way:

The second term drops out because , so all you have to do is plug in the numbers:

In other words, the total distance traveled is 402 meters, or a quarter-mile. Must be a quarter-mile racetrack.