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Q13.3: NCERT Physics - Part 2 OSCILLATIONS 13.3 Solution: Figure 13.18 depicts four x-t plots for linear motion of a…
⚠️ Common Exam Traps & Conceptual Pitfalls
Students often mistake a single repeated position for periodic motion, overlooking that the *entire* x‑t pattern must repeat over equal time intervals; verify that the whole trajectory, not just one point, recurs before labeling the motion periodic.
Figure 13.18 depicts four x-t plots for linear motion of a particle. Which of the plots represent periodic motion? What is the period of motion (in case of periodic motion)?
Step-by-Step Verified Solution
**Answer:** Plots (b) and (d) represent periodic motion with period 2 s. Plots (a) and (c) do not represent periodic motion.
**Step-by-Step Explanation:**
(a) This plot represents unidirectional, linear uniform motion. There is no repetition of motion, so it is not periodic [citation:13].
(b) The motion of the particle repeats itself after 2 s. Hence, it is periodic motion with a period of 2 s [citation:13].
(c) The particle repeats the motion in one position only. For periodic motion, the entire motion must be repeated in equal intervals of time. Hence, it is not periodic [citation:13].
(d) The motion of the particle repeats itself after 2 s. Hence, it is periodic motion with a period of 2 s [citation:13].
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