A permanent-magnet dc motor has the following parameters: Ra = 0.3 Ω and kE = kT = 0.5 in MKS units. For a torque of up to 10 Nm, plot its steady state torque-speed characteristics for the following values of Va: 100 V, 75 V, and 50 V.

Answer:

a) the minimum time (minutes) for the aluminium casting to solidify is 2.86 min

b) the minimum time (minutes) for the grey iron casting to solidify is 2.13 min. Therefore solidification of grey iron cast will take less time (2.13 min) compared to the solidification of the aluminium cast (2.86 min)

Explanation:

Given that; diameter of Disk = 500 mm, thickness t = 20, mold constant Cm = 2.0 sec/mm²

first we find the volume and Area;

Volume V = πD²t / 4

Volume V = π × (500)² × 20 / 4 = 3,926,991 mm³

Area A = 2πD²/ 4 + πDt

Area A = {[π × (500)²] / 2} +{ π × (500) × (20)}

Area A = 392,699.08 + 31,415.93

Area A = 424,115 mm²

a)

Chvorinov’s rule

T(aluminium) = Cm (V/A) ²

T(aluminium) =  2.0 × (3,926,991 / 424,115) ²

T(aluminium) = 171.5 s = 2.86 min

∴ the minimum time (minutes) for the casting to solidify is 2.86 min

b)

For cast iron

Cm (mold constant = 1.488 sec/mm²)

Chvorinov’s rule

T(iron) = Cm (V/A) ²

T(iron) = 1.488 × (3,926,991 / 424,115) ²

T(iron) = 127.5720s = 2.13 min

Therefore solidification of grey iron cast will take less time (2.13 min) compared to the solidification of the aluminium cast (2.86 min)

Explanation:

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Answer:

A)  ( N ) = 1.54

B)  N ( Goodman ) = 1.133,  N ( Morrow) = 1.35

Explanation:

width of steel bar = 25-mm

thickness of steel bar = 10-mm

diameter = 6-mm

load on plate = between 12 kN AND 28 kN

notch sensitivity = 0.83

A ) Fatigue factor of safety based on yielding criteria

= δa + δm = [tex]\frac{Syt}{n}[/tex]   =  91.03 + 227.58 = 490 / N

therefore Fatigue number of safety ( N ) = 1.54

δa (amplitude stress ) = kf ( Fa/A) = 2.162 * ( 8*10^3 / 190 ) = 91.03 MPa

A = area of steel bar = 190 mm^2 , Fa = amplitude load = 8 KN , kf = 2.162

δm (mean stress ) = kf ( Fm/A ) = (2.162 * 20*10^3 )/ 190 = 227.58 MPa

Fm = mean load  = 20 *10^3

B) Fatigue factor of safety based on Goodman and Morrow criteria

δa / Se + δm / Sut = 1 / N

= 91.03 / 183.15 + 227.58 / 590 = 1 /N

Hence N = 1.133 ( based on Goodman criteria )

note : Se = endurance limit (calculated) = 183.15 , Sut = 590

applying Morrow criteria

N =   1 / ( δa/Se) + (δm/ δf )

   = 1 / ( 91.03 / 183.15 ) + (227.58 / 935 )  

   = 1.35

Answer:

Logging while drilling (LWD) is a technique of conveying well logging tools into the well borehole downhole as part of the bottom hole assembly (BHA). ... In these situations, the LWD measurement ensures that some measurement of the subsurface is captured in the event that wireline operations are not possible

Answer: Tl = - 13.3°C

the lowest outdoor temperature is - 13.3°C

Explanation:

Given that;

Temperature of Th = 21°C = 21 + 273 = 294 K

the rate at which heat lost is Qh = 5400 kJ/h°C

the power input to heat pump Wnet = 6 kw

The COP of a reversible heat pump depends on the temperature limits in the cycle only, and is determined by;

COPhp = Th/(Th - Tl)

COPhp = Qh/Wnet

Qh/Wnet = Th/(Th -Tl)

the amount of heat loss is expressed as

Qh = 5400/3600(294 - Tl)

the temperature of sink

( 5400/3600(294 - Tl)) / 6 = 294 / ( 294 - Tl)

now solving the equation

Tl = 259.7 - 273

Tl = - 13.3°C

so the lowest outdoor temperature is - 13.3°C

Answer:

the torque required to RAISE the load is Tr = 18.09 Nm

the torque required to LOWER the load is Tl = 10.069 ≈ 10.07 Nm

the Overall Efficiency e = 0.2199 ≈ 0.22

Explanation:

Given that; F = 5 kN, p = 5mm, d = 35mm

Dm = d - p/2

Dm = 35 - ( 5/2) = 35 - 2.5

DM = 32.5mm

So the torque required to RAISE the load is

Tr = ( 5 × 32.5)/2 [(5 + (π × 0.09 × 32.5)) / ( (π × 32.5) - ( 0.09 × 5))] + [( 5 × 0.06 × 45)/2]

Tr = 81.25 × (14.1892 / 101.6518) + 6.75

Tr = 11.3414 + 6.75

Tr = 18.09 Nm

the torque required to LOWER the load is

Tl =  ( 5 × 32.5)/2 [(π × 0.09 × 32.5) - 5) / ( (π × 32.5) + ( 0.09 × 5))] + [( 5 × 0.06 × 45)/2]

Tl = 81.25 × 4.1892 / 102.5518 + 6.75

Tl = 3.3190 + 6.75

Tl = 10.069 ≈ 10.07 Nm

So since torque required to LOWER the load is positive

that is, the thread is self locking

Therefore the efficiency is

e = ( 5 × 5 ) / ( 2π × 18.09 )

e = 25 / 113.6628

e = 0.2199 ≈ 0.22

Answer:

  11.94 V

Explanation:

Generally the regulated voltage drops as load increases. When the voltage has dropped by 0.5%, it will be 60 mV less than the nominal value:

  12.0 V - 0.06 V = 11.94 V . . . . full load voltage

Answer:

Check it out here

Explanation:

Answer:

b. inversely proportional to radius of curvature

Explanation:

In curvilinear motions, the normal acceleration which is also called the centripetal acceleration is always directed towards the center of the circular path of motion. This acceleration has a magnitude that is directly proportional to the square of the speed of the body undergoing the motion and inversely proportional to the radius of the curvature of the motion path. The centripetal or normal acceleration a,  can be given by;

a = [tex]\frac{v^2}{r}[/tex]

Where;

v = speed of the body

r = radius of curvature.

Answer:

The answer is below

Explanation:

1) The synchronous speed of an induction motor is the speed of the magnetic field of the stator. It is given by:

[tex]n_s=\frac{120f_s}{p}\\ Where\ p\ is \ the \ number\ of\ machine\ pole, f_s\ is\ the\ supply \ frequency\\and\ n_s\ is \ the \ synchronous\ speed(speed \ of\ stator\ magnetic \ field)\\Given: f_s=60\ Hz, p=4. Therefore\\\\n_s=\frac{120*60}{4}=1800\ rpm[/tex]

2) The speed of the rotor is the motor speed. The slip is given by:

[tex]Slip=\frac{n_s-n_m}{n_s}. \\ n_m\ is\ the \ motor\ speed(rotor\ speed)\\Slip = 0.05, n_s= 1800\ rpm\\ \\0.05=\frac{1800-n_m}{1800}\\\\ 1800-n_m=90\\\\n_m=1800-90=1710\ rpm[/tex]

3) The frequency of the rotor is given as:

[tex]f_r=slip*f_s\\f_r=0.04*60=2.4\ Hz[/tex]

4) At standstill, the speed of the motor is 0, therefore the slip is 1.

The frequency of the rotor is given as:

[tex]f_r=slip*f_s\\f_r=1*60=60\ Hz[/tex]

Answer:

  leakage

Explanation:

That current is "leakage current."

Answer:

some of the professions and human resource related to engineering are:

Aerospace engineering involves the study, design and development of spacecrafts using Core science principles.

Electrical engineering involves the study and application of core science principles especially physics and mathematics into providing Electrical related solutions

Explanation:

Engineering is a major branch of applied science. In general Engineering is concerned with the design and building of engines ( i.e. application of scientific/science facts   )

some of the professions and human resource related to engineering are:

Aerospace engineering involves the study, design and development of spacecrafts using Core science principles.

Electrical engineering involves the study and application of core science principles especially physics and mathematics into providing Electrical related solutions

Answer:

A) The relative humidity : 0.818 (81.8%), Temperature at C = 14.4⁰c

B) The rate of energy destruction = 0.0477 kw  

Explanation:

Given data :

at point 1 : m1 = 3 kg/min , T1 = 30⁰c, p1 = 1 bar,  ∅ = 0.50 ( 50%)

at point 2 : T2 = 5⁰c,  P2 = 1 bar, m2 = 5 kg/min

at point 3 : p3 = 1 bar

Answer: y' = - x'

Explanation:

Let f(x) = 2x + y

then f'(x) = 2 + y'

Let f(y) = x - 2y

then f'(y) = x' - 2

Given:  f'(x) + f'(y) = 0

         2 + y' + x' - 2 = 0

                y' + x'= 0

                 y' = -x'

This can also be written as:       [tex]\dfrac{dy}{dx}=-\dfrac{d}{dx}[/tex]

Answer:

  resistance

Explanation:

A strain gauge changes resistance with applied strain.

Answer:

a. 115

b. 135

c. 220

d. 185

Explanation:

Spheriodite is microscopic constituents in some steels which is composed of spherically shaped cementide particle. It is most ductile and softest type of steel. Pearlite is two phased lamellar compose of alternating layer of ferrite and cementite. It is hard and strong but not tough. It is applied on cutting tools like chopper, blades and knives.

Answer:

current is measured in Ampere (A)

Answer:

Ampere (A)

Explanation:

The ampere is defined so the elementary charge e is 1.602 176 634 × 10−19 C or A•s.

Hope this helps <3

solution from c hegg. hope it helps. see photos explanation

Answer:

Explanation:

MOSFET: The acronym for  "metal oxide semiconductor field-effect transistor"  are mostly used in switching circuits.

There are two classes of MOSFET

1. Depletion mode

2. Enhancement mode

          Generally a  MOSFET is a kind of transistor, it is actually a field effect transistor with tree terminals gate, source and drain terminals, also the MOSFET can be used as an amplifier for the amplification of electronic signals in the electronic circuit/devices

Answer:

A) EXIT TEMPERATURE = 14⁰C

b) rate of heat transfer of air = - 13475.78 = - 13.5 kw

Explanation:

Given data :

diameter of duct = 20-cm = 0.2 m

length of duct = 12-m

temperature of air at inlet= 50⁰c

pressure = 1 atm

mean velocity = 7 m/s

average heat transfer coefficient = 85 w/m^2⁰c

water temperature = 5⁰c

surface temperature ( Ts) = 5⁰c

properties of air at 50⁰c and at 1 atm

= 1.092 kg/m^3

Cp = 1007 j/kg⁰c

k = 0.02735 W/m⁰c

Pr = 0.7228

v  = 1.798 * 10^-5 m^2/s

determine the exit temperature of air and the rate of heat transfer

attached below is the detailed solution

Calculate the mass flow rate

= p*Ac*Vmean

= 1.092 * 0.0314 *  7 = 0.24 kg/s

Answer:

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while n<1:

c=(n!)/((n-r)!(r!))

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Answer:

forward voltage triggering

temperature triggering

dv/dt triggering

light triggering

gate triggering

Then turning off;

Turn off is accomplished by a "negative voltage" pulse between the gate and cathode terminals

Explanation:

hope it helps

Answer:

hello your question has some missing part attached below is the complete question

answer : steady state temperature = 419.713k ≈ 218.7⁰c

              Time required to reach a junction ≈ 5 secs

Explanation:

The detailed solution of the given problem is attached below but the solution to the subsequent problem from which the question you asked is referenced to( problem 1 ), is not attached because it was not part of the question you asked

Answer:

say in English plz I don't understand

Answer:

A) 13.80 ft/s^2

B) 1.714 Ib

Explanation:

Magnitude of acceleration center G

mass = W / g = 8 / 32.2 = 0.2484 Ib.s^2/ft

calculate the acceleration along x direction

A = ra

r = radius

a = angular acceleration

A = 6 in [tex]\frac{1 ft}{12 in}[/tex] * a

a= 2A

equation of the plane along the x-direction

w sin∅ - F = ma

8* sin40 - F = 0.2484 * a

hence F = 5.1423 - 0.2484 a

next find the moment of inertia along the z axis

I = 1/2 mr^2

  = 1/2 * 0.2484 * (6/12)^2  = 0.03105 Ib.ft.s^2

Applying moment balance equation

F * r = inertia * a

(5.1423 - 0.2484 a)*0.5 = 0.03105 * 2A

2.57115 = 0.1863 A      hence

A = 13.80 ft/s^2  ( acceleration of the cylinder )

B) Calculate the friction force exerted by the ramp on the cylinder

F = 5.1423 - 0.2484 A

  = 5.1423 - 0.2484 ( 13.80 )

  = 1.714 Ib

The magnitudes of the acceleration and the friction force are;

Acceleration = 13.8 ft/s²

Friction Force = 1.714 lb

The image of the solid homogeneous cylinder is missing and so i have attached it.

From the image we see that;

We are given;

      We know that formula for weight is; W = mg

Thus; m = W/g

where g is acceleration due to gravity = 32.2 ft/s²

m = 8/32.2

mass; m = 0.2484 lb.s²/ft

     Now, to get the acceleration along the x-axis, we will use the formula;

a = rα

where α is angular acceleration. Thus;

a = 0.5α

α = 2a   ----- (eq 1)

    Now, resolving forces along the x-direction gives;

W*sinθ - F = ma

Plugging in the relevant values;

8*sin 40 - F = 0.2484a

F = 8*sin 40 - 0.2484a    -----(eq 2)

     Now, moment of inertia of the cylinder along the z-axis is gotten from;

I = ¹/₂mr²

I = ¹/₂ × 0.2484 × 0.5²

I = 0.03105 lb.ft/s²

     Taking equilibrium of moments we have;

F*r = I*α

Thus;

(8*sin 40 - 0.2484a)0.5 = 0.03105α

⇒ 2.57115 - 0.1242a = 0.03105α

⇒ 0.03105α + 0.1242a = 2.57115

From eq 1, α = 2a. Thus;

0.03105(2a) + 0.1242a = 2.57115

0.1863a = 2.57115

a = 2.57115/0.1863

a = 13.8 ft/s²

F = 8*sin 40 - 0.2484a

F = 5.1423 - 0.2484(13.8)

F = 1.714 lb

Read more about cylinder moment of inertia at; https://brainly.com/question/7020147

Answer:

nosenose

Explanation:

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Answer: A prototype

Explanation:

The scale model that proves the initial concept is called a domain model.

A copy or depiction of something where all parts have the same dimensions as the original. A scale model is an image or copy of an object that is either larger or smaller than the object being represented's actual size.

A domain model is a type of conceptual model that is used to depict the structural elements and conceptual constraints within a domain of interest.

A domain model will include all of the entities, their attributes, and relationships, as well as the constraints that govern the conceptual integrity of the structural model elements that comprise that problem domain.

Therefore, a domain model is the scale model that proves the initial concept.

To learn more about the scale model, refer to the below link:

https://brainly.com/question/14341149

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Answer:

Electrical conductivity or specific conductance is the reciprocal of electrical resistivity. It represents a material's ability to conduct electric current. It is commonly signified by the Greek letter σ (sigma), but κ (kappa) (especially in electrical engineering) and γ (gamma) are sometimes used.

Answer:

Horizontal component ( Ax) = 0

vertical component ( Ay ) = 1794.87 N

Explanation:

Attached below is the detailed solution and the free body diagram of the question

given data:

density = 7910 kg/m3

thickness of plate = 9 mm = 0.009

determine the horizontal and vertical components of the reaction at the pin A and the tension in the cable BC