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The position of a particle moving along the x-axis is given by x = (6t - t² + 36) m, where t is measured in seconds. Find the length of the time interval (in seconds) during which the particle moves in the positive x-direction.
- 2 s
- 3 s
- 6 s
- 9 s
Correct answer: 3 s
Solution
The velocity v = 6 - 2t is positive for t < 3 s and negative for t > 3 s. Assuming the particle starts at t = 0, it moves in the positive x-direction for exactly 3 seconds.
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