InterviewSolution
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InterviewSolution
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straight road from his home to market 2.5 km away with a speed ofCample 4. A man walks on a road5 kmis the magnitude of average velocity, and average speed of the man over the interval of timerample 4. A man waaiet close, he instantly turns and walks back with a speed of 7.5 km h.Whatwalks on aFinding the market closed, he instantly tu(i) 0 to 30 min,(l0 to 50 min, (ii) 0 to 40 min ? |
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Answer» Time taken by the man to reach the market from home,t1= 2.5/5 = 1/2 h = 30 minTime taken by the man to reach home from the market,t2= 2.5/7.5 = 1/3 h = 20 minTotal time taken in the whole journey = 30 + 20 = 50 min (i) 0 to 30 minAverage velocity = Displacement/Time = 2.5/(1/2) = 5 km/hAverage speed = Distance/Time = 2.5/(1/2) = 5 km/h (ii) 0 to50 minTime = 50 min=50/60 = 5/6 hNet displacement = 0Total distance = 2.5 + 2.5 = 5 kmAverage velocity = Displacement / Time = 0Average speed = Distance / Time = 5/(5/6) = 6 km/h(iii) 0 to 40 minSpeed of the man = 7.5 km/hDistance travelled in first 30 min = 2.5 kmDistance travelled by the man (from market to home) in the next 10 min= 7.5×10/60 = 1.25 kmNet displacement = 2.5 – 1.25 = 1.25 kmTotal distance travelled = 2.5 + 1.25 = 3.75 kmAverage velocity = Displacement/Time = 1.25/(40/60)= 1.875 km/hAverage speed = Distance/Time = 3.75/(40/60) = 5.625 km/h |
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