Write a function called echo that takes as argument a list and returns a copy of that listwith each element duplicated right after it. here are some examples of how your program should behave on python idle. > > > echo(['a','b','c'])['a', 'a', 'b', 'b', 'c', 'c']> > > echo(['x','y'])['x', 'x', 'y', 'y']> > > echo([85, 72, 61])[85, 85, 72, 72, 61, 61]> > > echo([85, "abc", 6.79])[85, 85, 'abc', 'abc', 6.79, 6.79]

Ajournal bearing has a journal diameter of 3.250 in with a unilateral tolerance of 20.003 in. the bushing bore has a diameter of 3.256 in and a unilateral tolerance of 0.004 in. the bushing is 2.8 in long and supports a 700-lbf load. the journal speed is 900 rev/min. find the minimum oil film thickness and the maximum film pressure for both sae 20 and sae 20w-30 lubricants, for the tightest assembly if the operating film temperature is 160°f. a computer code is appropriate for solving this problem.

What is the major difference between thermoplastics and thermosetting plastics from the polymerization structure point of view?

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?