Six crates(a, b,c, d,e, f) at rest on level surfaces. The crates have differentmasses and the frictional coefficients [given as(μs,μk)] between the crates and the surfaces differ. Thesame external force is applied to each crate, but none of thecrates move.

Rank the crates on the basis of thefrictional force acting on them.
Rank from largest to smallest.

a. [500kg μ=(0.6,0.3)]

b. [750kg μ=(0.4,0.3) ]

c. [250kg μ=(0.2,0.1)]

d.[600kg μ=(0.8,0.5)]

e.[750kg μ=(0.6,0.5)]

f. [1500kg μ=(0.3,0.1) ]

Which is not a characteristic of a heat pump? a. it is used in air conditioners. b. it uses a refrigerant. c. it requires no work. d. it reverses the normal flow of thermal energy.

In a series circuit the __ is the same at every point

4r-134a enters the condenser of a residential heat pump at 800 kpa and 50°c at a rate of 0.022 kg/s and leaves at 750 kpa subcooled by 3°c. the refrigerant enters the compressor at 200 kpa superheated by 4°c determine (a) the isentropic efficiency of the compressor, (b) the rate of heat supplied to the heated room, and (c) the cop of the heat pump. also, determine (d) the cop and rate of heat supplied to the heated room if this heat pump operated on the ideal vapor-compression cycle between the pressure limits of 200 and 800 kpa. (0.757, 4.37 kw, 5.12, 6.18, 3.91 kw)