An adiabatic piston-cylinder device with no leaks executes expansion work during which 2 kg of saturated liquid water at atmospheric pressure (101.325 kPa) is completely turned into saturated steam. What is the entropy generated for this process? (Use proper units)
*Please write clearly and directly note any references to property tables!*
In: Mechanical Engineering
low carbon steel having a tensile strength of 350 MPa and shear strength of 250 MPa is cut in a turning operation with a cutting speed of 200 m/min. The feed is 0.3 mm/rev and the depth of cut is 4.8 mm. The rake angle of the tool is 12 degrees in the direction of chip flow. The resulting chip ratio is 0.8. Using the orthogonal model as an approximation of turning determine...
a.The shear plane angle.
b. Shear force
c. Cutting force
d. Friction force
e. Normal force to shear and coefficient of friction.
f. Cutting power and cutting horsepower.
In: Mechanical Engineering
Saturated water vapor at 300°F enters a compressor operating at
steady state with a mass flow rate of 5 lb/s and is compressed
adiabatically to 650 lbf/in.2
If the power input is 2150 hp, determine for the compressor:
(a) the percent isentropic compressor efficiency and
(b) the rate of entropy production, in hp/°R.
Ignore kinetic and potential energy effects.
In: Mechanical Engineering
a. Consider a parabolic cam profile consisting of a rise-dwell-return-dwell cycle where the rise-cycle to full lift (L= 0.33 in) occurs over a 60° segment of shaft rotation. The shaft is turning at a constant speed of 100rpm. What is the velocity, acceleration and jerk of the follower at the mid-point of the rise-cycle?
b. If the profile was now changed to a simple harmonic profile, what is the velocity, acceleration and jerk of the follower at the mid-point of the rise-cycle?
c. If the profile was now changed to a cycloidal profile, what is the velocity, acceleration and jerk of the follower at the mid-point of the rise-cycle?
In: Mechanical Engineering
8–7 For the screw clamp shown, a force is applied at the end of
the handle 3.5
in from the screw
centerline. The 3/8
in diameter handle is made of cold-drawn AISI 1006 steel. The screw
is
3/4
in-10 UNC and is 8 in long, overall. The maximum possible length of
screw in the clamping
region is 6 in.
(a) What screw torque will cause the handle to bend
permanently?
(b) What clamping force will the answer to part (a) cause if the
collar friction is neglected and
if the thread friction is 0.15?
(c) What clamping force will cause the screw to buckle?
(d) Are there any other stresses or possible failures to be
checked?
In: Mechanical Engineering
Consider a residential heat pump that uses lake water as the heat source in the winter and as heat sink inthe summer. The house is to maintained at a winter temperature of T= 18 degrees C and a summer temperature of T= 25 degrees C. To do this efficiently, it is found that the indoor coil should be at T= 50 degrees C in the winter and T= 5 degrees C in the summer. The outdoor coil temperature can be assumed to be T= 5 degrees C during the winter months and T= 35 degrees C during the summer. Using R-134a as the working fluid.
For the winter months,
(a) The coefficient of performance for a Carnot heat pump cycle operating at the given temperatures.
(b) Determine the temperature and pressures at the principal states of the cycle.
(c) The power input to the compressor, in kJ/kg.
(d) The thermal efficiency (coefficient of performance)
In: Mechanical Engineering
In: Mechanical Engineering
Choose the best option:
- Viscoelastic stress relaxation
- Viscoelastic creep
Although the viscoelastic response of a polymer can be very complex (time-dependent stress cycling for instance), two special loading scenarios are fairly simple to describe mathematically.
1. _______ refers to scenarios for which the stress applied to a polymer must decay over time in order to maintain a constant strain. Otherwise, over time, the polymer chains will slip and slide past one another in response to a constant applied load and the strain will increase (in magnitude).
2. ________ refers to scenarios for which a polymer will permanently flow over time in response a constant applied stress.
In: Mechanical Engineering
Nanoparticles are often added to polymer matrix to enhance various properties, the interaction with the polymer largely determines the state of the nanoparticle in the polymer matrix. Describe two of these state and one dispersing method that can achieved the most desirable state.
please no hand writing
In: Mechanical Engineering
Write a MATLAB script or function that returns the required initial velocity of the ping pong ball required to launch it a specified distance. Use projectile motion equations. Keep in mind that the initial firing height will change depending on the proposed catapult design.
Primary considerations in the catapult design are accuracy and repeatability as groups will be tasked with hitting the target (cup) repeatedly at distances ranging from 7 to 9 ft. (cup moved in 6 in. increments).
In: Mechanical Engineering
A first-order pressure sensor must meet the following dynamic response specifications: (a) At least 95% accuracy within 0.09s after a step input. (b)The delay corresponding to a ramp input of 60 psi/s is less than 0.02s. (c) Steady-state error of no more than 1 psi for a ramp input of 100 psi/s. (The dynamic error for an input ramp corresponds to the following definition: (d) The dynamic error is to be held smaller than 10% for measuring a turbulent flow with fluctuations of up to 30 Hz. Find a transfer function which has the largest allowable time constant for this sensor.
In: Mechanical Engineering
Why are principles, laws and axioms useful in science and engineering?
| a) | Without principles science and engineering can be unethical |
| b) | They provide an overarching understanding that can be applied to a wide variety of problems |
| c) | They make disciplines harder to learn and teach so only top students can master them |
| d) | They recognize and exploit the commonalities in a class of problems and solutions to facilitate finding solutions |
| e) | All of the above |
| f) | a and b only |
| g) | b and d only |
In: Mechanical Engineering
A firm has discovered that its sales are highly correlated to a certain economic parameter. The value for that parameter has been predicted to be 15 for the next year (7th year). Use regression modeling to develop a forecast for the next year.
|
Year |
1 |
2 |
3 |
4 |
5 |
6 |
|
Econ. Parameter |
16.2 |
14.9 |
18.5 |
16.1 |
13.8 |
15.4 |
|
# Sales |
120 |
100 |
165 |
140 |
100 |
110 |
In: Mechanical Engineering
True or False
1. Shafts utilized for constant power transmission with no supported components may be designed using static failure theory.
2. Slope and deflection of shafts are constrained to ensure proper functionality of the supported components
3. For a given bending moment loading and length, a shaft with smaller diameter will result in smaller angular deflection at the bearing supports.
4. For a shaft subjected to combined variable bending and constant torsional loading, the shaft diameter at the critical location can be determined using Gerber theory
5. A shaft that satisfies deflection constraints for a given loading will have an infinite life
6. Langer failure theory best predicts fatigue failure of shafts under variable bending and torsion
7. Material of the shaft is chosen such that strength is greater than applied loading at critical location in order to ensure desired life and meet reliability requirements.
In: Mechanical Engineering
A kanban system has a rate of delivery, which equals the rate of arrival to the system, of 60 batches in a 10-hr day. Each batch contains 8 parts, and the processing time of a batch is exactly 8 minutes. The time between arrivals is known to have the exponential distribution. Compute the proportion of time the system is busy (?), the lead time, and the WIP (in terms of batches).
In: Mechanical Engineering