Rotations per Minute . How many rotations per minute must a wheel of diameter 1.5 m make to
achieve a speed of 45 kmph ? (Approx pi= 3 ).
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To find the number of rotations per minute, we can use the formula:
Rotations per minute = (Speed in meters per hour) / (Circumference of the wheel in meters)
To calculate the speed in meters per hour, we need to convert 45 kmph into meters per hour. Since 1 km = 1000 m and 1 hour = 3600 s, we can calculate the speed as follows:
Speed in meters per hour = 45 kmph * (1000 m / 1 km) * (1 hour / 3600 s)
Speed in meters per hour = (45000 m) / (3600 s)
Speed in meters per hour = 12.5 m/s
Now let's calculate the circumference of the wheel using the formula:
Circumference of the wheel = Diameter of the wheel * pi
Circumference of the wheel = 1.5 m * 3
Circumference of the wheel = 4.5 m
Finally, we can use the formula mentioned earlier to calculate the rotations per minute:
Rotations per minute = (Speed in meters per hour) / (Circumference of the wheel in meters)
Rotations per minute = (12.5 m/s) / (4.5 m)
Rotations per minute ≈ 2.78 rotations per minute
Therefore, the wheel must make approximately 2.78 rotations per minute to achieve a speed of 45 kmph.