When operated at N = 1170 rpm, a centrifugal pump, with impeller D = 8in., has a shutoff head ho = 25.0 ft of water. At the same operating speed, best efficiency occurs at Q = 300 gpm, where the head is h = 21.9 ft of water. Fit these data at 1170 rpm with a parabola. Scale the results to a new operating speed of 1750 rpm. Plot and compare the results.

Supercharging of an engine is used to increase the inlet air density so that more fuel can be added, the result of

which is an increased power output. Assume that ambient air, 100 kPa and 27°C, enters the supercharger at a rate

of 250 L/s. The supercharger (compressor) has an isentropic efficiency of 75%, and uses 20 kW of power input.

Assume that the ideal and actual compressor have the same exit pressure. Find the ideal specific work and verify

that the exit pressure is 175 kPa. Find the percent increase in air density entering the engine due to the

supercharger and the entropy generation

Identify the trend of using sensors in the transportatoin (cars) area over time
Describe change over three stages (time periods). Add references used.

Initial:

Middle

Recent:

Water flows through a shower head steadily at a rate of 8 kg/min. The water is heated in an electric water heater from 158C to 458C. In an attempt to conserve energy, it is proposed to pass the drained warm water at a temperature of 388C through a heat exchanger to preheat the incoming cold water. Design a heat exchanger that is suitable for this task, and discuss the potential savings in energy and money for your area.

A hollow, round column has length (L = 1500 mm), outside diameter (do = 20 mm) and inside diameter (di = 14 mm). If the column is made of steel (E = 207 GPa, Sy = 300 MPa), then determine if it is a Johnson or an Euler column and find the critical load Pcr for each of the following end-conditions:

(a) Pinned-pinned

(b) Fixed-pinned

(c) Fixed-fixed

(d) Fixed-free

Noncubic ceramics are birefringent. Explain why this is important for polycrystalline alumina nose cones.

Explain briefly why the transparency range of single-crystal NaCl is much greater than for single- crystal MgO.

A sheet of metal of 2 m ´ 2 m and 1.5 mm thickness is being tested in a wind tunnel.

a. Calculate the critical velocity, in m/s, at which the boundary layer will remain laminar.

b. For an upstream velocity of 35 m/s, what percentage of the metal sheet surface will have a laminar boundary layer.

c. For each of the previous cases (all laminar B.L and mixed laminar/turbulent B.L), calculate the drag force on the plate, in N. Use Table 9.3 to calculate the appropriate drag coefficients.

Consider a spherical vessel filled with a substance which is generating heat at a uniform rate of 10^5 W/m^3. The substance has a thermal conductivity of 20 W/mK, and the vessel has a thermal conductivity of 15 W/mK.

The inner radius of the container is 0.5m and the outer radius is 0.6 m.

The container is surrounded by a fluid with convection coefficient of 1000 W/m^2K and T_inf = 25 Celsius.

Determine the temperature distribution T(r) by solving the differential equation, and evaluating the given boundary conditions

Perform sit-­up exercises under the following conditions: 1) arms folded across the chest, 2) hands behind the neck, 3) holding a five­ pound weight above the head. Write a paragraph explaining your findings and draw a free body diagram showing the Applied Force, Resistance, and Axis of rotation.

Explanation:

?Free body diagram:

Derive an expression for the U factor if the inside and outside surfaces of the tubes in a heat exchanger are finned and have fin efficiencies of ?_i and ?_o on the inside and the outside, and A_f,i and A_f,o as the finned area on the inside and the outside, respectively, and similarly A_u,i and A_u,o as the unfinned area on the inside and the outside, respectively.

Please post all steps taken. Thanks!

A single axis personal transport device starts from rest with the rider leaning slightly forward. Together, the two wheels weigh 25 lbs, and each has a radius of 10 in. The mass moment of inertia of the wheels

about the axle is 0.15 slug ft². The combined weight of the rest of the device and the rider (excluding the wheels) is 200 lbs, and the center of gravity G of this weight is located at x = 4 in. in front of the

axle A and y = 36 in. above the ground. An initial clockwise torque M is applied by the motor to the wheels. The coefficients of static and kinetic friction are 0.7 and 0.6, respectively.

4. Given a system of five (5) 3500-lb, 700 feet per minute (fpm) elevator cars. Gearless traction motors are being used for this system. Each car operates approximately 65% of the time and while in operation, each car draws 96% of the full load. Calculate

a. Heat generated in the machine room during peak periods. Assume solid-state control is used. (5 points)

b. Assume the following operation profile during a 24-hour day

5 hours peak use

3 hours of 70% peak

4 hours of 50% peak

12 hours of 10% peak

Calculate the approximate monthly energy cost using the electricity rate of $0.10/kWh assuming 25 days of operation per calendar month (10 points)