Arefrigerator using r-12 as the working fluid keeps the refrigerated space at −15℃ in an environment at 30℃. you are asked to upgrade this refrigerator by replacing r-12 with the ozone-friendly r-134a or ammonia.
a. what are the temperatures and pressures of the three refrigerants at every stage of the cycle?
b. in / what are work input and heat removal for each refrigerant?
c. what is the cop for each refrigerant? based on cop only, which one would you pick?
d. based on other engineering considerations, which refrigerant would you pick? why?
answer with explanation:
when dealing with heavy loads, one needs to take certain precautions in order to avoid or prevent from injuries.
for instance, one should avoid lifting above the shoulder level which can end up pulling your muscle.
also, you can either break the load in parts if possible or get some for lifting heavy bulks.
moreover, one should try to lift with the legs while keeping the back straight and not twisting it.
answer & explanation:
"the force on a cutting tool are 2600n vertically downward" sounds a little unusual, since most of the time, the tool is above the object to be cut in such a way that the force acting "on the tool" is upwards. we will accept the statement as it is (downwards).
since the two forces are acting at right angles to each other, the resultant can be found using pythagoras theorem, namely
resultant = sqrt(2600^2+2100^2) = 3342 n (approx.)
the angle can be found using the arctangent function, or
angle = arctangent(2600/2100) = 51.07 degrees below the horizontal, since the 2600 n force is acting downwards.
the drive force for diffusion is 7 fick's first law can be used to solve the non-steady state diffusion.
efficiency of reversible power cycles operating between a hot re