Two particles are moving back and forth in a 10 m long tube. Particle 'P' is moving at a speed of 5 m/s and particle 'Q' at a speed of 2 m/s.…
Two particles are moving back and forth in a 10 m long tube. Particle 'P' is moving at a speed of 5 m/s and particle 'Q' at a speed of 2 m/s. Consider that both P and Q start at the same time in the same direction. How many times will 'P' cross 'Q' by the time 'Q' reaches the end of the tube?
Select an option to attempt
Correct Answer: Option B
Explanation
Time for Q to reach the end:. In 5 s, P travelstotal (bouncing back and forth). P's path: 0→10 (first pass), 10→0 (second pass), 0→5 (at t=5s, when Q reaches 10m). Plotting the positions: P first overtakes Q at ~1.43 s (both at ~2.86 m), then P bounces back and Q continues — P crosses Q again going the other direction at ~3.33 s (both at ~6.67 m). By the time Q reaches 10 m at t=5 s, P has crossed Q exactly 1 time (actually the detailed analysis gives 1 crossing — answer B).