Question 4. Determine the time needs to fill completely $4 S3 $2 $1 the tank when all pipes are open together? if you know that: 1. If ONLY Pipe S1 is open, it needs 10 seconds to fill this tank by its self. 2. If ONLY Pipe S2 is open, it needs 20 seconds to fill this tank by its self. 3. If ONLY Pipe S3 is open, it needs 30 seconds to fill this tank by its self. 4. If ONLY Pipe S4 is open, it needs 40 seconds to fill this tank by its self. Problem 5 Calculate the heat transfer rate from a 1000 m, 6 cm thick concrete wall with inside and outside surface temperatures of 20'C and OC respectively. The conductivity thermal coefficient of the concrete is equal to 1.4 W/m K. Page 3 | 6