Question

please answer this question..
how is it being done!

Answer 1

Given, Diameter of the wheel d = 140 cm.

Then, radius of the wheel r = d/2 = 70 cm.

We know that Circumference of the wheel = 2πr.

⇒ 2 * (22/7) * 70

⇒ 440 cm.

Given, Speed of the wheel = 66 km per hour.

Distance covered in 1 minute = (66 * 1000 * 100)/60 cm

                                                 = 6600000/60

                                                 = 110000 cm.

Hence, the number of revolutions made by the wheel in 1 minute:

⇒ Total distance covered/Circumference

⇒ 110000/440

⇒ 250.

Therefore, The wheel must make 250 revolutions per minute.

Hope it helps!

Answer 2

Solution:
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diameter of the wheel = 140 cm

radius of the wheel = diameter ÷ 2

= 140 ÷ 2 = 70 cm

distance covered in 1 revolution
= circumference of wheel

= 2πr = (2 × 22 × 70) / 7


= 440 cm

speed of wheel = 66 km/ hr

distance covered in 1 hour=66 km

= 66 × 1000 × 100 = 6600000 cm

distance covered in 1 min

= 6600000 ÷ 60 = 110000 cm

revolution made by the wheel in 1 min

= distance covered in 1 min. ÷ distance covered in 1 revolution.

= 110000 ÷ 440 = 250

Answer: 250 revolutions
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