Question

the wheel of loco engine, 7.5 meters in radius, makes 7 revolutions in 9 seconds. The speed of train in km/h would be

Answer 1

we know circumference of circle is 2πr
2×22/7×7.5=86.30m
then it makes 7 revolutions in 9 sec
7×86.30 = 9sec
9seconds = 605
so for 1second 605/9 = 67.22.
If wrong answer it

Answer 2

Answer:132

Step-by-step explanation:

Perimeter of circle(wheel)

= 2πr = 2 * 22/7 * 7.5 is distance

cover in in one revolutions.

7 revolutions in 9 seconds, therefore revolution in 1 Second is 7/9

therefore Distance cover in 1 Second is 2 * 22/7 * 7.5 * 7/9

i.e. distance cover in 1 hour equal to = 2 * 22/7 * 7.5 * 7/9 * 3600 = 13200 meter/hr

i.e. speed of the train in Km = 132Km/hr