NHJKNET72

83問 • 2年前

問題一覧

A concave opherical mirror has a focal length of 12 cm. If an object 16 placed 6 cm in front of it, the image position is:

12 cm in front of the mirror

The usual function of a disconnect switches in high voltage circuits is to

isolate from energized buses, equipment which are not in service

Which of the following is NOT a valid plotting command in MATLAB?

Prod

How tall does a wall mirror have to be in order for you to see all of yourself in the mirror? Imagine you stand a distance "d' from the mirror and your height is "h" and I is the length of mirror required.

L = 1/2 h

What is the most essential attribute of a project manager?

Leadership

IEBE 1284 is a standard communication that defines

parallel communication

In Ra 7920, "commission" refers to

PRC

Cross linking of natural rubbers called

Vulcanization

Which of the following thermodynamic relations is incorrect?

U = Q -W

Specific atom of an isotope is called

Nuclide

Which is more desirable? I. Investing P 2000 at 68 per year compounded interest for three years. II. Investing P2000 per year simple interest for three years.

A 0.15 mdimeter pipe discharges into a 0.10-m diameter pipe. Determine the velocity head (meter/g) in the 0.10-m diameter pipe if the pipes are carrying 0.12 m*3/s of kerosene.

10.93

In a crystal structure, what is an interstitial atom?

an extra atom sitting at a nonlattice point

Which of the following statements is FALSE?

wavelength of visible light > wavelength of microwaves

If all variables in a linear programming problem are restricted to be integers, which, if any, basic assumption of linear programming is violated?

divisibility

Consider a nontrivial linear programming problem in one variable, , with only lower- and upper-bound constraints on 2. At optimum, where will « be in relation to these constraints?

at its upper or lower bound

If a project that has diminishing returns with scale is modeled using a linear program, which basic assumption of linear programming will be violated?

proportionality

As the simplex algorithm progresses from one solution to the next in a linear programming maximization problem, what will happen to the value of the objective function?

It will increase or stay the same.

Upon which of the following properties of linear programming is the simplex method based? I. The collection of feasible solutions constitutes a convex set. II. If a feasible solution exists, a basic solution exists where the feasible solutions correspond to the extreme points of the set of feasible solutions. III. Only a finite number of basic feasible solutions exist. IV. If the objective function possesses a finite maximum, at least one opti- mum solution is a basic feasible solution.

I II III and IV

Which of the following describes the optimum solution to a transportation problem?

It can be determined using the simplex algorithm.

If an integer programming problem is solved as a linear programming problem and the resulting values of the decision variable are rounded off, which of the following will result?

an integer solution that may be optimum, or close to it

For which of the following is the Program Evaluation and Review Technique (PERT) NOT used?

queueing problems

Which of the following is NOT a good application of network analysis?

inventory theory

What are the basic features of dynamic programming problems? I. The problem can be divided into stages with a policy decision required at each stage. II. Each stage has a number of states associated with it. III. The effect of the policy decisions at each stage is to transform the current state into a state associated with the next stage. IV. The problem formulation is dependent on the probability distribution associated with it.

I II and III

Identify the FALSE statement.

PERT evaluates the sensitivity to changes in the program.

Queueing theory provides a large number of alternative mathematical models for describing which of the following?

waiting line problems

Which of the following statements about dynamic programming is FALSE?

Dynamic programming can be represented in standard mathematical for-mulation.

In a queueing process of customers in a store, what statistical pattern will most likely describe the arrival of customers over time?

the Poison distribution

Which of the following statements is FALSE?

The acceleration of any point within a homogenous body rotating with a constant angular velocity is proportional to the distance of that point to the center of mass.

Which of the following statements is FALSE?

The coefficient of restitution can be less than zero.

How many degrees of freedom does a coin rolling on the ground have?

three

For a rectangular beam under transverse (bending) loading, where is the location of maximum shear stress?

at the neutral axis

The allowable tensile stress for a 6.25 mm diameter bolt with a thread length of 5.5 mm is 207 MPa. The allowable shear stress of the material is 103 MPa. Where and how will such a bolt be most likely to fail if placed in tension? (Assume threads are perfectly triangular and that the force is carried at the mean thread height.)

at the threads due to shear

Under which type of loading does fatigue occur?

repeated load

Where do stress concentrations occur? I. near the points of application of concentrated loads II. along the entire length of high distributed loads Ill. at discontinuities

I and III

Which of the following would most likely require a steel containing 0.6% carbon that has been spheroidized, cold-drawn, and slightly tempered?

a cutting tool

Which of the following statements is FALSE?

Addition of small amounts of silicon to steel can cause a marked decrease in yield strength of the steel.

Which of the following statements is FALSE?

Low-alloy steels are a minor group and are rarely used.

In preparing a metallographic iron specimen, the grain boundaries are made most visible by which of the following steps?

etching the sample in a 2% solution of nitric acid in alcohol

Ductile cast iron and gray cast iron both contain 4% carbon. Ductile cast iron, however, has a higher tensile strength and is considerably more ductile. Which of the following is the major difference that accounts for the superior properties of the ductile iron?

The gray cast iron contains flakes of graphite, whereas the ductile iron contains spheroids of graphite.

The equilibrium cooling of a steel containing 0.8% carbon results in a product with little use because it is extremely brittle. Which of the following is the primary reason for this poor characteristic?

The carbide forms thin plates that are brittle.

Low-carbon steels are generally used in the "as rolled" or "as fabricated" state. What is the reason for this?

Their strength generally cannot be increased by heat treatment.

Which of the following phases of steel has a face-centered cubic structure?

austenite

Which of the following is NOT a structural class of steels?

tool and die

On an alloy phase diagram, what is the solidus temperature?

The temperature of the solid phase at which the first liquid forms for a given overall composition.

Two pieces of copper are brazed together using a eutectic alloy of copper and silver. The braze material melts at 780°C. If a second braze is attempted in order to attach another piece of copper, which of the following is true?

The first braze will not melt at 780°C, but the second braze will.

Which of the following is the correct representation of a eutectic cooling reaction? (The subscripts denote different compositions.)

(liquid) ---> (solid)2 + (solid)2

What is transformed in a eutectoid reaction? (A) One liquid is transformed into two solids of different composition. (B) A solid becomes a liquid at the eutectic temperature. (C) A liquid becomes a solid at the solidus temperature. (D) A solid becomes a liquid at the liquidus temperature.

How can an ordered solid solution be distinguished from a compound? (A) In an ordered solid solution, the solute atoms occupy interstitial positions within the lattice. (B) The solute atoms in an ordered solid solution substitute for atoms in the parent lattice. (C) The atoms in an ordered solid solution form layers in the lattice structure. (D) When heated, an ordered solid solution becomes disordered before melting.

Which of the following is NOT an important criterion for forming a complete binary solid solution? (A) The difference in radii should be less than 15%. (B) The constituent elements must have the same crystal structure. (C) The atoms should be close to one another in the periodic table. (D) The difference in atomic numbers should be small.

Of the following inorganic glasses, which have tetrahedral lattice structures? SiO2, B203, BeF2, GeO2

SiO2, BeF2, and GeO2

Which statement (s) describe(s) the glass transition temperature? I. It is the temperature at which the rate of volume contraction decreases abruptly. Il. It is the temperature at which residual stresses in the glass can be relieved. III. It is the point where the material behaves more like a solid than a viscous liquid.

I and III

Which of the following describe(s) the modulus of elasticity of an elastomer? I. It is directly proportional to the number of cross links in the elastomer. II. Its value increases with temperature. III. It is directly proportional to the number of double bonds in the chemical structure.

I and II

Low-density polyethylene undergoes extensive (over 100%) elongation prior to rupture, while polystyrene undergoes only 1-2% elongation. What is the main reason for this difference? (A) The polyethylene is less dense. (B) The large styrene groups in the polystyrene prevent slippage. (C) More cross-linking occurs in the polystyrene. (D) Polyethylene is less crystalline.

What causes the vinyl interiors of automobiles to crack when subjected to prolonged direct sunlight? (A) the volatilization evaporation) of plasticizers (B) repetitive expansion and contraction of the plastic (C) oxidation of the plastic by sunlight and oxygen (D) all of the above

Which of the following correctly describes atoms located at grain boundaries? (A) They are subjected to the same type of interatomic forces that are present in the interior atoms of the crystal. (B) They are located primarily in highly strained and distorted positions (C) They have a higher free energy than atoms in the undisturbed part of the crystal lattice. (D) All of the above are correct.

Which of the following is FALSE? (A) Grain size is of minor importance in considering the properties of polycrystalline materials. (B) Fine-grained materials usually exhibit greater yield stresses than coarse. grained materials at low temperatures. (C) At high temperatures, grain boundaries become weak, and sliding occurs. (D) Grain boundary sliding is the relative movement of two grains by a shear movement parallel to the grain boundary between them.

Which of the following statements is FALSE?

Hot working causes much strain hardening of the metal.

Which of the following statements is FALSE?

Cold work decreases the yield point of metal.

Which of the following statements is FALSE?

The amount or percentage of cold work cannot be obtained from information about change in the area or thickness of a metal.

Which of the following docs cold working a metal cause?

elongation of grains in the flow direction, an increase in dislocation density, and an overall increase in energy of the metal

In general, what are the effects of cold working a metal?

increased strength, decreased ductility

Which of the following are true statements about the modulus of elasticity, E?

It is the slope of the stress-strain diagram in the linearly elastic region.

Which of the following does NOT produce vacancies, interstitial defects, or impurity defects in a material?

slow equilibrium cooling

Which one of these statements is true for twinning?

It frequently occurs in hexagonal close-packed structures.

As the amount of slip increases, additional deformation becomes more difficult and decreases until the plastic flow finally stops. Slip may begin again only if a larger stress is applied. What is this phenomenon known as?

strain hardening

The ease with which dislocations are able to move through a crystal under stress accounts for which of the following? I. ductility II. lower yield strength III. hardness

I and II

To which of the following can the large discrepancy between the actual and theoretical strengths of metals mainly be attributed?

dislocations

A shaft made of good quality steel breaks in half due to fatigue. What would the surface of the fracture site look like?

smooth over most of the surface, with tearing at the location of fracture

What does the Charpy impact test measure? I. the energy required to break a test sample Il. the strength of a test sample III. the ductile to brittle transition temperature of metals

I and III

Under conditions of very slow deformation and high temperature, it is possible to have plastic flow in a crystal at shear stresses lower than the critical shear stress. What is this phenomenon called?

Creep

Which of the following are true regarding creep? 1. It is caused by the diffusion of vacancies to edge dislocations, permitting dislocation climb. II. It involves the plastic deformation of materials at loads below the vield stress. III. It may involve whole grain sliding.

I, II, and III

Which of the following is true regarding the ductile-to-brittle transition temper-ature? I. It is important for structures used in cold environments. II. It is the point at which the size of the shear lip or tearing rim goes to zero. III. It is the temperature at which 20 J of energy causes failure in a Charpy -notch specimen of standard dimensions.

I and III

Which of the following best describes the 0.2% offset yield stress?

It is the stress at which the material plastically strains 0.2%.

Which of the following statements is FALSE?

The energy of an interior atom is greater than the energy of an atom on the surface of a liquid.

Which of the following are true about Fick's first law for diffusion? I. It is only applicable to gases and liquids, not solids. II. The law states that the flux moves from high to low concentration. 111. J, the flux, may be in units of cm°/em"s.

II and III

Which of the following statements regarding diffusion in a crystal structure is true?

It often uses an exchange or vacancy mechanism.

Which of the following is a line defect in a lattice crystal structure?

Screw dislocation

Comparing the face-centered cubic lattice with the hexagonal close-packed lat-tice, which of the following features describes the hexagonal close-packed structure only?

Its deformation properties are more directional.

Which of the following statements is FALSE regarding X-ray diffraction?

X-ray diffraction is only useful for studying simpler crystals such as the body-centered cubic structure, rather than more complex crystals like the hexagonal close-packed structure.

In a queueing process of customers in a store, what type of distribution most likely governs the time between consecutive arrivals of customers?

an exponential distribution

Of the following statements, which is FALSE?

The FORMAT statement may or may not be executed by the program.

Which of the following would have to be added to the main program as a result of the variable XINCH being changed to INCH? Before the change, the function is FUNCTION FOOT(XINCH) FOOT=XINCH 12.0 RETURN END

a REAL variable declaration

dhshsisn

dhshsisn

hshshsus

hshshsus

NHJNKET7

NHJNKET7

36626835

36626835

hdhshdve

hdhshdve

hshshshs

hshshshs

hshshsus

hshshsus

hshsvsus

hshsvsus

bnmkkh

bnmkkh

Ghghg

Ghghg

bsbdhjxbd

bsbdhjxbd

NHJNKET71

NHJNKET71

問題一覧

A concave opherical mirror has a focal length of 12 cm. If an object 16 placed 6 cm in front of it, the image position is:

12 cm in front of the mirror

The usual function of a disconnect switches in high voltage circuits is to

isolate from energized buses, equipment which are not in service

Which of the following is NOT a valid plotting command in MATLAB?

Prod

L = 1/2 h

What is the most essential attribute of a project manager?

Leadership

IEBE 1284 is a standard communication that defines

parallel communication

In Ra 7920, "commission" refers to

PRC

Cross linking of natural rubbers called

Vulcanization

Which of the following thermodynamic relations is incorrect?

U = Q -W

Specific atom of an isotope is called

Nuclide

Which is more desirable? I. Investing P 2000 at 68 per year compounded interest for three years. II. Investing P2000 per year simple interest for three years.

A 0.15 mdimeter pipe discharges into a 0.10-m diameter pipe. Determine the velocity head (meter/g) in the 0.10-m diameter pipe if the pipes are carrying 0.12 m*3/s of kerosene.

10.93

In a crystal structure, what is an interstitial atom?

an extra atom sitting at a nonlattice point

Which of the following statements is FALSE?

wavelength of visible light > wavelength of microwaves

If all variables in a linear programming problem are restricted to be integers, which, if any, basic assumption of linear programming is violated?

divisibility

Consider a nontrivial linear programming problem in one variable, , with only lower- and upper-bound constraints on 2. At optimum, where will « be in relation to these constraints?

at its upper or lower bound

If a project that has diminishing returns with scale is modeled using a linear program, which basic assumption of linear programming will be violated?

proportionality

As the simplex algorithm progresses from one solution to the next in a linear programming maximization problem, what will happen to the value of the objective function?

It will increase or stay the same.

I II III and IV

Which of the following describes the optimum solution to a transportation problem?

It can be determined using the simplex algorithm.

If an integer programming problem is solved as a linear programming problem and the resulting values of the decision variable are rounded off, which of the following will result?

an integer solution that may be optimum, or close to it

For which of the following is the Program Evaluation and Review Technique (PERT) NOT used?

queueing problems

Which of the following is NOT a good application of network analysis?

inventory theory

I II and III

Identify the FALSE statement.

PERT evaluates the sensitivity to changes in the program.

Queueing theory provides a large number of alternative mathematical models for describing which of the following?

waiting line problems

Which of the following statements about dynamic programming is FALSE?

Dynamic programming can be represented in standard mathematical for-mulation.

In a queueing process of customers in a store, what statistical pattern will most likely describe the arrival of customers over time?

the Poison distribution

Which of the following statements is FALSE?

The acceleration of any point within a homogenous body rotating with a constant angular velocity is proportional to the distance of that point to the center of mass.

Which of the following statements is FALSE?

The coefficient of restitution can be less than zero.

How many degrees of freedom does a coin rolling on the ground have?

three

For a rectangular beam under transverse (bending) loading, where is the location of maximum shear stress?

at the neutral axis

at the threads due to shear

Under which type of loading does fatigue occur?

repeated load

Where do stress concentrations occur? I. near the points of application of concentrated loads II. along the entire length of high distributed loads Ill. at discontinuities

I and III

Which of the following would most likely require a steel containing 0.6% carbon that has been spheroidized, cold-drawn, and slightly tempered?

a cutting tool

Which of the following statements is FALSE?

Addition of small amounts of silicon to steel can cause a marked decrease in yield strength of the steel.

Which of the following statements is FALSE?

Low-alloy steels are a minor group and are rarely used.

In preparing a metallographic iron specimen, the grain boundaries are made most visible by which of the following steps?

etching the sample in a 2% solution of nitric acid in alcohol

The gray cast iron contains flakes of graphite, whereas the ductile iron contains spheroids of graphite.

The carbide forms thin plates that are brittle.

Low-carbon steels are generally used in the "as rolled" or "as fabricated" state. What is the reason for this?

Their strength generally cannot be increased by heat treatment.

Which of the following phases of steel has a face-centered cubic structure?

austenite

Which of the following is NOT a structural class of steels?

tool and die

On an alloy phase diagram, what is the solidus temperature?

The temperature of the solid phase at which the first liquid forms for a given overall composition.

The first braze will not melt at 780°C, but the second braze will.

Which of the following is the correct representation of a eutectic cooling reaction? (The subscripts denote different compositions.)

(liquid) ---> (solid)2 + (solid)2

Of the following inorganic glasses, which have tetrahedral lattice structures? SiO2, B203, BeF2, GeO2

SiO2, BeF2, and GeO2

I and III

I and II

Which of the following statements is FALSE?

Hot working causes much strain hardening of the metal.

Which of the following statements is FALSE?

Cold work decreases the yield point of metal.

Which of the following statements is FALSE?

The amount or percentage of cold work cannot be obtained from information about change in the area or thickness of a metal.

Which of the following docs cold working a metal cause?

elongation of grains in the flow direction, an increase in dislocation density, and an overall increase in energy of the metal

In general, what are the effects of cold working a metal?

increased strength, decreased ductility

Which of the following are true statements about the modulus of elasticity, E?

It is the slope of the stress-strain diagram in the linearly elastic region.

Which of the following does NOT produce vacancies, interstitial defects, or impurity defects in a material?

slow equilibrium cooling

Which one of these statements is true for twinning?

It frequently occurs in hexagonal close-packed structures.

strain hardening

The ease with which dislocations are able to move through a crystal under stress accounts for which of the following? I. ductility II. lower yield strength III. hardness

I and II

To which of the following can the large discrepancy between the actual and theoretical strengths of metals mainly be attributed?

dislocations

A shaft made of good quality steel breaks in half due to fatigue. What would the surface of the fracture site look like?

smooth over most of the surface, with tearing at the location of fracture

What does the Charpy impact test measure? I. the energy required to break a test sample Il. the strength of a test sample III. the ductile to brittle transition temperature of metals

I and III

Creep

I, II, and III

I and III

Which of the following best describes the 0.2% offset yield stress?

It is the stress at which the material plastically strains 0.2%.

Which of the following statements is FALSE?

The energy of an interior atom is greater than the energy of an atom on the surface of a liquid.

II and III

Which of the following statements regarding diffusion in a crystal structure is true?

It often uses an exchange or vacancy mechanism.

Which of the following is a line defect in a lattice crystal structure?

Screw dislocation

Comparing the face-centered cubic lattice with the hexagonal close-packed lat-tice, which of the following features describes the hexagonal close-packed structure only?

Its deformation properties are more directional.

Which of the following statements is FALSE regarding X-ray diffraction?

X-ray diffraction is only useful for studying simpler crystals such as the body-centered cubic structure, rather than more complex crystals like the hexagonal close-packed structure.

In a queueing process of customers in a store, what type of distribution most likely governs the time between consecutive arrivals of customers?

an exponential distribution

Of the following statements, which is FALSE?

The FORMAT statement may or may not be executed by the program.

a REAL variable declaration