The radius of a bicycle wheel is 40 cm. The wheel makes 85 revolutions in 1 minute. Find the speed of the bike.

Before finding the speed of a bicycle, you should determine the circumference of its wheel.

To do this, multiply the product of the radius and the constant number P (P = 3.14) by 2.

Will be:

2 * 3.14 * 40 = 3.14 * 80 = 251.2 cm.

We convert the circumference to meters.

Since there is 100 cm in 1 meter, we get:

251.2 / 100 = 2.512 m.

Find the speed of the bike.

We multiply the circumference by the number of perfect revolutions in 1 minute.

2.512 * 85 = 213.52 m / min.

Answer: The speed of the bike is 213.52 m / min.