Which option distinguishes the step in the engineering design phase described in the following scenario? Inexpensive hockey helmets are not keeping Pee Wee hockey players from suffering concussions after blows to the head.

defining the need
doing an analysis
researching the problem
brainstorming solutions

Apiping systems consists of 6 m of 6-std type k and 12 m of 4-std type k, both drawn copper tubing. the system conveys ethylene glycol at a rate of 0.013 m3/s. the pressure drop across the system is to be calculated. there are two 90° elbows in the 6-in pipe, a reduction from the 6-in pipe to the 4-in pipe and four 90° elbows in the 4-in pipe. all fittings are soldered (same as flanged) and regular. the inlet and outlet of the system are at the same height.