Engineering Answers

The position function of Superman’s motion in the x-axis is given by x(t) = e^t cos(2t) + 4t^3 − t sin(t).

Use meters for the position and seconds for time.

a. Find the displacement of Superman from t = 0s to t = 5s.

b. What is the velocity of Superman for any given t? Find the velocity of Superman when t = 5s.

c. Find the acceleration function for Superman’s motion. Did he slow down or speed up when t = πs? Explain.

8. A 75% efficient cooling tower has a water entering at 45o C and wet bulb temperature of air entering at

25 oC. Find the water exit temperature of water. PLEASE EXPLAIN THE DETAILED ANSWER/SOLUTION.

ANSWER:

A. 32oC B. 30oC C. 34.34oC D. 23.44oC

7. A 6 x 5 x 4 m room has a pressure of 101 kpa and temperature of 30oC (Psat = 5 kpa). If percent

relative humidity is 65%, find the mass of vapor (RV = 0.423 KJ/kgoK).

ANSWER:

A. 0.345 kg B. 1.23 kg C. 3.04 kg D. 2.19 kg

6. Air in a conditioned space has 26 oC db and 70% RH, find the wet bulb depression. PLEASE EXPLAIN THE DETAILED ANSWER/SOLTION.

Answer:

A. 6.00 oC B. 15.34 oC C. 7.20 oC D. 17.80 oC

6. A throttling calorimeter is connected to the superheated steam line supplying steam to the auxiliary feed

pump on a ship. The line pressure measures 2.5 Mpa. The calorimeter pressure is 110 kpa and 150oC.

Determine the entropy of the steam line. PLEASE EXPALIN THE DETAILED ANSWER/SOLUTION.

ANSWER: a. 6.8 KJ/kg-oK c. 6.6 KJ/kg-oK

b. 6.2 KJ/kg-oK d. 7.5KJ/kg-oK

Air goes through a Brayton cycle gas turbine, entering the compressor at 21 C and 107 kPa. When it reaches the turbine inlet, the air is at 884 C and 1.36 MPa. What is the net change in specific enthalpy of the working fluid after going through the compressor and heat addition processes? You may assume that the specific heat capacity c. is a constant 1.005 kJkg 1-K throughout the whole cycle. Give your answer in kJ-kg^-1 to one decimal place.