There is a double tube exchanger, in which you have glycerin flowing in the inner tube at a rate of 2.5 Kg / s, it enters at a temperature of 600 ° C and it exits at a temperature of 100 ° C, and from the outside you have water which enters at a temperature of 20 ° C, at a rate of 1.0 Kg / s, if the resistance to total heat flow is 150 KW/m^2*K, determine the value of the conduction coefficient of the pipe, if the inner pipe it is nominal 1 1/2 "Schedule 80, and the outer piping is nominal 2" Schedule 80. The system is in parallel with flows large enough to neglect convection.

Agroup of students is studying convection current. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other is in an area with warm air. after 10 minutes, the balloon are released from a height of 1 meter. which of the following to the students most likely observe? a) the warm balloon expands and rises. the cold balloon shrinks and sinks b) the balloon both rise. the cold balloon is larger than the warm balloon c) the cold balloon expands and rises. the warm balloon shrinks and sinks d) the balloon rise at the same rate. both balloons are the same size