The blades of a windmill sweep out a circle of area A. If the wind flows at a velocity v perpendicular to the circle, what is the mass of the air passing through it in time t?
The cylindrical tube of a spray pump has a cross-section of \(8.0\) cm2 one end of which has \(40\) fine holes each of diameter \(1.0\) mm. If the liquid flow inside the tube is \(1.5\) m-min–1, the speed of ejection of the liquid through the holes is:
1. \(0.64\) ms-1
2. \(0.74\) ms-1
3. \(0.54\) ms-1
4. \(0.84\) ms-1