Answer
In this question, we are given the rates of mass entering and the rates of mass exit. here we will apply mass conservation directly , as hot or cold , it is water (not any other state), so we are free to apply mass conservation i.e
net mass flow rate =
$mass_{1in }$/second + $mass_{2in }$/second - $mass_{3out }$/second = 1.2+0.8 - 2.5= -0.5lb/sec. Therefore after 1 hour,
Mass left in the container = initial mass + (mass flow rate)$\times$(time);
and 1 hour = 3600 seconds.
so mas left= 2000 + (-0.5)$\times$(3600)=200 lb.
Work Step by Step
In this question, we are given the rates of mass entering and the rates of mass exit. here we will apply mass conservation directly , as hot or cold , it is water (not any other state), so we are free to apply mass conservation i.e
net mass flow rate =
$mass_{1in }$/second + $mass_{2in }$/second - $mass_{3out }$/second = 1.2+0.8 - 2.5= -0.5lb/sec. Therefore after 1 hour,
Mass left in the container = initial mass + (mass flow rate)$\times$(time);
and 1 hour = 3600 seconds.
so mas left= 2000 + (-0.5)$\times$(3600)=200 lb.
