Water at 20 °c flows at 3 m/s in a tube with a diameter of 50 mm. a) what is the pressure drop over 30 meters if the walls of the tube are smooth? water at 20 °c flow at 3 m/s in the annulus of a concentric tube heat exchanger. the inner wall of the annulus has a diameter of 25 mm and the outer wall a diameter of 50 mm. what is the pressure drop over 30 meters if: b) the walls are taken as smooth? c) the walls are made of commercial steel?

Tom is having a problem with his washing machine. he notices that the machine vibrates violently at a frequency of 1500 rpm due to an unknown rotating unbalance. the machine is mounted on 4 springs each having a stiffness of 10 kn/m. tom wishes to add an undamped vibration absorber attached by a spring under the machine the machine working frequency ranges between 800 rpm to 2000 rpm and its total mass while loaded is assumed to be 80 kg a) what should be the mass of the absorber added to the machine so that the natural frequency falls outside the working range? b) after a first trial of an absorber using a mass of 35 kg, the amplitude of the oscillation was found to be 10 cm. what is the value of the rotating unbalance? c) using me-3.5 kg.m, find the optimal absorber (by minimizing its mass). what would be the amplitude of the oscillation of the absorber?