A ball rolls down from the top of an incline with a height of 5 m high without slipping. The ball has a diameter of 0.2m. What are the ball’s translational speeds a) at the center of the ball, b) at the contact point on the ground, and c) at the top of the ball when it arrives at the bottom? What values of "c" do you expect for hollow/solid balls? Will the hollow ball be faster?
In: Mechanical Engineering
A nuclear power plant based on the Rankine cycle operates with a
boiling-water reactor to develop net cycle power of 3 MW. Steam
exits the reactor core at 100 bar, 620°C and expands through the
turbine to the condenser pressure of 1 bar. Saturated liquid exits
the condenser and is pumped to the reactor pressure of 100 bar.
Isentropic efficiencies of the turbine and pump are 81% and 78%,
respectively. Cooling water enters the condenser at 15°C with a
mass flow rate of 114.79 kg/s.
Determine:
(a) the percent thermal efficiency.
(b) the temperature of the cooling water exiting the condenser, in
°C.
In: Mechanical Engineering
2.21 Use IHT to perform the following tasks.
(a) Graph the thermal conductivity of pure copper,
2024 aluminum, and AISI 302 stainless steel over
the temperature range 300 T 600 K. Include
all data on a single graph, and comment on the
trends you observe.
(b) Graph the thermal conductivity of helium and air
over the temperature range 300 T 800 K.
Include the data on a single graph, and comment on
the trends you observe.
(c) Graph the kinematic viscosity of engine oil,
ethylene glycol, and liquid water over the tempera-
ture range 300 T 360 K. Include all data on
a single graph, and comment on the trends you
observe.
(d) Graph the thermal conductivity of a water-Al2O3
nanofluid at T 300 K over the volume fraction
range 0 0.08. See Example 2.2.
In: Mechanical Engineering
In matlab.write a program that converts a numerical date given by the user into a month, day, and year. Specifically, the user should input a sequence of eight numbers 05141956.
the program should print out the same date in complete format. In this example it would print "The date is May 14th, 1956". Notice the "th" addition after the day. This changes depending on the number. Make sure this feature is included. MATLAB has built-in date conversion functions. You cannot use them in this exercise.
In: Mechanical Engineering
If you were given the choice to make the laptop cover of steel
or
polymers. Which do you prefer and why?
In: Mechanical Engineering
1. A flywheel is the shape of a sphere of radius R. Calculate the stored energy again for rotation time T and total mass M. Do not attempt to use moment of inertia or rotational mechanics, do it the way we did in class.
2. Find an exercise calorie website, and for a 70 kg person walking on a treadmill at 5 kilometers per hour, by varying the grade of the treadmill, plot the work output power (of lifting the person) vs. the fuel (food) consumption input power of the person. That is, for different grades, (% incline), find the fuel consumption in watts, and calculate the work output of the person lifting themselves against gravity, and plot work output vs. fuel consumption. Note that a 10 % grade means climbing 15 feet for every 100 feet of horizontal travel, so you will have to a little trigonometry here. What is the differential efficiency of the person, that is, for dx increase in fuel consumption, which results in dy increase in work output, the differential efficiency is dy/dx. Where does the input power that does not result in useful lifting work go?
In: Mechanical Engineering
You are designing an aircraft to fly slowly at high altitude, so you want to minimize induced drag. Which of the following statements best describes the likely shape of the wing you will design?
| A. |
The best wing for this mission will be short and stubby, like the wing on an F-104 |
|
| B. |
The best wing for this mission will be a delta wing, like the wing on an F-106 |
|
| C. |
The best wing for this mission will have a very high aspect ratio, like the wing on the U-2 |
|
| D. |
The aspect ratio of the wing does not matter, since it has no effect on induced drag |
In: Mechanical Engineering
Review the two videos (1) “Steam Power Plant” and (2) Gas Turbine. For each one, identify at least three examples of the design for each of the following criteria:
1. Energy performance (e.g. improved efficiency, higher power output, ...)
2. Economic considerations (reduced cost)
3. Environmental considerations (reduced emissions, etc.).
* Link of video 1 - https://youtu.be/xokHLFE96h8
Click on 1st video (how a thermal power plant works)
* Link of video 2 - https://youtu.be/GF-70yncAVY
Click on industrial gas turbine working principle
In: Mechanical Engineering
Uniform internal heat generation at q˙ = 2.00 × 107 W/m3 is occurring in a cylindrical nuclear reactor fuel rod of 50-mm diameter, and under steady-state conditions the temperature distribution is of the form T(r)=a+br^2, where T is in degrees Celsius and r is in meters, while a= 800 °C and b= -4.167 × 105 °C/m2. The fuel rod properties are k= 30 W/m·K, ρ= 1100 kg/m3, and cp= 800 J/kg·K.
Find the steady state temperature gradient, dT/dr, at the outer surface of the rod, in °C/m.
What is the steady state rate of heat transfer at the outer surface, in W/m?
Immediately after the sudden increase in reactor power level (at t= 0 sec), what is the temperature at the centerline?
Immediately after the sudden increase in reactor power level (at t= 0 sec), what is the time rate of temperature change, dT/dt, at the centerline, in °C/s?
In: Mechanical Engineering
In one or two sentences describe the corrosion failure mode. What is one visual cue to indicate corrosion? Does corrosion always necessitate part replacement?
In: Mechanical Engineering
In: Mechanical Engineering
Say that you are looking to buy a small call and want to get a very efficient car. You are trying to decide between a hybrids car and an electric car. Hyundai offers the Ioniq in a hybrid gas and an all-electric model. Compare these models by filling in the table below.
Measure 2017 Ioniq blue 2017 Ioniq electric
MPG combined (epa)
MPG city (epa)
MPG highway (epa)
CO2 produced per mile (g/mi) in Columbia, Mo Fuel cost to drive 25mi ($)
Horse power (hp)
Torque (ft-lbf)
Range (mi)
Which would you buy and why?
In: Mechanical Engineering
1. A 150-kg sewing machine operates at 1200 RPM and has a rotating unbalance of 0.45 kg-m. What is the max stiffness of an undamped isolator such that the force transmitted to the machine’s foundation is less than:
a) 1547
b) 2547
2. Redesign helicopter seat (i.e. find new stiffness) so that the maximum velocity experienced by the pilot is 1 mm/sec.
In: Mechanical Engineering
use matlab:
A cable of length Lc supports a beam of length Lb so that it is horizontal when the weight W is attached to the beam end. The tension force T in the cable is given by the following equation: T=(Lb*Lc*W)/(D*sqrt(Lc^2-D^2)) Where D is the distance of the cable attachment point to the beam pivot. 1. Create a function M-file that evaluates the tension T as a function of D. In this function M-file the parameters Lb, Lc, and W should be declared global. 2. Create a script M-file that creates these global variables and: a) Prompts for and accepts the following values from the Command Window : W = 400N, Lb= 5 m, and Lc = 3 m (the weight is in Newtons, and the lengths are in meters) b) Uses these values and the fminbnd function to compute and display in the Command Window the value of D that minimizes the tension, T, and the minimum tension value. c) Uses fzero to determine by how much the value of D can vary from it
In: Mechanical Engineering
Find the value of the thermal conductiviity of the following substance at the given conditions:
AISI 316 Stainless Steel at 300K
In: Mechanical Engineering