what is meant by alarms for fires?
a) Volume mass / density 2 kg/1000 kg/m^3 0.002 m^3b) Area of cross section of the nozzle A1 π d^2/4 3.14*0.01^2 /4 0.000008 m^2 Mass rate of flow 2kg/m^2: Volume rate of flow 0.002 m^3 /s Volume rate of flow Area * velocity Velocity v1 Volume rate of flow / Area 0.002 / 0.000008 250 m/s c) Area of cross section of the hose A2, Velocity is v2. A2 *v2 A1*v1 v2 [A1 /A2] *v1 [d1/d2]*v1 [1/2.5]* 250 100 m/s d) Change in momentum mass (final velocity - initial velocity} 2*(250- 100) 300 kg*m/s e) By Newton's second law F rate of change in momentum 300 /time 300/time. Since in every second there is a change in momentum of 300 kg m/s . The force is 300 N. By Newton's third law, for every force of action, there is equal but opposite force called reaction. The force needed to apply is - 300N. Minus sign indicates that the force is to be applied opposite to the direction of motion.
A speed bump. I refer to his short but disastrous tenure with what he calls a teachable moment. We will learn from this mistake and smooth that road out.
