The speed of which liquid must move through a pipe with a radius of 15 cm so that the flow rate is 20 liters per second?

Task data: r (radius of the pipe along which the fluid moves) = 15 cm (0.15 m); V (volume of liquid passed through the pipe; liquid flow rate) = 20 l (0.02 m3); t (time of fluid movement) = 1 s.

The speed of fluid movement through the pipe is calculated by the formula: Vw = S / t = h / t = (V / S) / t = V / (Π * r2 * t).

Calculation: Vw = 0.02 / (3.14 * 0.152 * 1) = 0.283 m / s.

Answer: The liquid must move through the pipe at a speed of 0.283 m / s.