Technician A says the Delta T method of adjusting the charge levels of the refrigerant system relies on a comparison of the inlet and outlet temperatures of the evaporator. Technician B says systems should always be checked first for refrigerant contamination. Who is correct

Acarpenter builds an exterior house wall with a layer of wood 2.9 cm thick on the outside and a layer of styrofoam insulation 2.3 cm thick on the inside wall surface. the wood has k=0.080w/(m⋅k), and the styrofoam has k= 0.010 w/(m⋅k). the interior surface temperature is 19.0 ∘c , and the exterior surface temperature is -15.0 ∘c . a.)what is the temperature at the plane where the wood meets the styrofoam? celsius b.)what is the rate of heat flow per square meter through this wall? /m^2

On a horizontal frictionless surface, a small block with mass 0.200 kg has a collision with a block of mass 0.400 kg. immediately after the collision, the 0.200 kg block is moving at 12.0 m/s in the direction 30° north of east and the 0.400 kg block is moving at 11.2 m/s in the direction 53.1° south of east. use coordinates where the +x-axis is east and the +y-axis is north.(a) what is the total kinetic energy of the two blocks after the collision (in ) what is the x-component of the total momentum of the two blocks after the collision? (indicate the direction with the sign of your ) what is the y-component of the total momentum of the two blocks after the collision? (indicate the direction with the sign of your answer.)

A1500 w electric heater is plugged into the outlet of a 120 v circuit that has a 20 a circuit breaker. you plug an electric hair dryer into the same outlet. the hair dryer has power settings of 600 w, 900 w , 1200 w, and 1500 w. you start with the hair dryer on the 600 w setting and increase the power setting until the circuit breaker trips. under what setting does the circuit breaker trip.