Answer:
V=14.71 m/s

Step-by-step explanation:
Given that
Diameter d= 8 cm
Total pressure = 200 Pa (gauge)
Static pressure = 70 Pa (gauge)
We know that
Total pressure =Static pressure + Dynamic pressure

Density of air at room temperature

Now by putting the values

V=14.71 m/s
When diameter is reduced to 4 cm
For same flow rate
We know that




