The proportioning of a concrete mixture has resulted in the following SSD weights. Material WSSD (Ib/yd^3) Other Info
Cement 739 Gs=3.15
Rock (coarse) 1550 Gs(SSD)= 2.7, % tot= 6%, % abs= 0.8%
Sand (fine) ? SSD =2.6, % tot=1.4%, % abs= 1.4%
Water 325
Air ___ % Air =7%

1. What is the volume of sand required?

a. 6.45 ft^3
b. 6.94 ft^3
c. 8.83 ft^3
d. 9.66 ft^3

2. What is the batch water weight?

a. 230 lbs
b. 245 lbs
c. 325 lbs
d. 405 lbs

During a steady flow process, the change of energy with respect to time is zero. a)- true b)- false

Determine whether or not it is possible to compress air adiabatically from k to 140 kpa and 400 k. what is the entropy change during this process?

Along 8-cm diameter steam pipe whose external surface temperature is 900c connects two buildings. the pipe is exposed to ambient air at 70c with a wind speed of 50 km/hr blowing across the pipe. determine the heat loss from the pipe per unit length. (b) air at 500c enters a section of a rectangular duct (15 cm x 20 cm) at an average velocity of 7 m/s. if the walls of the duct are maintained at 100c. a) the length of the tube for an exit temperature of the air to be 40 0c. b)the rate of heat transfer from the air. c) the fan power needed to overcome the pressure drop in this section of the duct.