Repeat Example 2-7 using the equations of motion.
Solution
Restating the problem. Although the question asks for a distance traveled during a time interval, it is often convenient to assume that the object in question is starting out at x = 0 and t = 0. (This is just a matter of deciding where to put your origin and when to start your stopwatch.) With this assumption, Δx = x − xo = x − 0 = x and Δt = t − 0 = t. The question then becomes x = ? when t = 5 s.
What we know/what we don't.
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Choice of approach. Because the acceleration a is unknown, we first solve Equation 2-9 for a. Once a is known, you can use Equation 2-11 to find x.
The mathematical solution. Solving Equation 2-9 for a gives
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 Related homework: Problem 2-38. |