Last updated at May 29, 2018 by Teachoo
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Ex 12.1, 4 The wheels of a car are of diameter 80 cm each. How many complete revolutions does each wheel make in 10 minutes when the car is travelling at a speed of 66 km per hour? Number of revolutions = (๐๐๐ก๐๐ ๐๐๐ ๐ก๐๐๐๐)/(๐ท๐๐ ๐ก๐๐๐๐ ๐๐๐ฃ๐๐๐๐ ๐๐ 1 ๐๐๐ฃ๐๐๐ข๐ก๐๐๐) Diameter of circle = 80 cm radius = r = 80/2 = 40 cm Distance covered in one revolution = Circumference of wheel = 2 ๐r = 2 ร๐ร40 = 80ฯ cm Now, we find total distance covered We know that, Speed = ๐ท๐๐ ๐ก๐๐๐๐/(๐๐๐๐ ) Here, Speed = 66 km/hr Time = 10 minutes = 10/60 hour = 1/6 hour Putting value in formula 66 = Distance/(1/6) 66 ร1/6 = Distance 11 = Distance Distance = 11 km Distance = 11 km = 11 ร 1000 m = 11000 m = 11000 ร100 cm = 1100000 cm Now , Number of revolutions = (๐๐๐ก๐๐ ๐๐๐ ๐ก๐๐๐๐)/(๐ท๐๐ ๐ก๐๐๐๐ ๐๐๐ฃ๐๐๐๐ ๐๐ 1 ๐๐๐ฃ๐๐๐ข๐ก๐๐๐) = 1100000/80ฯ = 110000/8ฯ = 110000/(8 ร 22/7) = (110000 ร 7)/(8 ร 22) = 4375 Hence, number of revolutions = 4375
Chapter 12 Class 10 Areas related to Circles
Chapter 12 Class 10 Areas related to Circles
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