20. An extruder barrel has a diameter of 5.0 in and a length-to-diameter ratio of 22. The viscosity of the polymer melt = 0.0020 lb-s/in2 . The pitch of the screw = 4.5 in and channel depth = 0.25 in. The screw rotates at 50 rev/min, generating a head pressure = 500 lb/in2 . What is the volume flow rate of plastic at the die end of the barrel? 21. An extrusion operation produces continuous tubing with outside diameter = 2.0 in and inside diameter = 1.7 in. The extruder barrel has a diameter = 4.0 in and length = 10 ft. The screw rotates

The y form of iron is known as: a) ferrite b) cementite c) perlite d) austenite

Aloaded platform of total mass 500 kg is supported by a dashpot and by a set of springs of effective stiffness 72 kn/m. it is observed that when the platform is depressed through a distance x = 12.5 cm below its equilibrium position and then released without any initial velocity; it reaches its equilibrium position in the shortest possible time without overshoot. find the position and velocity of the loaded platform 0.10 sec. after its release. if a further load of 400 kg is added to the platform, find, i) the frequency of damped vibrations, and i) the amplitude of vibration after 2 complete oscillations, given that the initial amplitude is 15 cm.

The thermal expansion or contraction of a given metal is a function of the f a)-density b)-initial temperature c)- temperature difference d)- linear coefficient of thermal expansion e)- final temperature f)- original length