Question

A bicycle has wheels with a diameter of 42cm.
The bicycle is ridden in a straight line at a constant speed. The wheel makes 250
revolutions per minute.
What is the speed of the bicycle in kilometres per hour?

Answer 1

Answer:

diameter = 49cm;

radius = diameter/2 = 24.5cm;

circumference = 2πr ≈ 153.94 = 154cm

1 revolution = 154cm

50 revolution = 7700cm = 77m

I hope I am correct.

Answer 2

$v = wr$

$v = 2\pi(250)(0.21) \frac{60}{1000} = 19.8 \frac{km}{h}$