A bronze statue weighing 4 tonnes with a base of area 0.8 m2 is placed on a granite museum floor. The yield strength of the bronze is 240 MPa. What is the true area of contact, between the base and the floor?

Given:

[tex]\sigma _{s} = 2.8\times 10^{4} \Omega-m[/tex]

electron concentration, n = [tex]2.9\times 10^{22} m^{-3}[/tex]

[tex]\mu _{h} = 0.14[/tex]

[tex]\mu _{e} = 0.023[/tex]

Solution:

Let holes concentration be 'p'

[tex]\sigma _{s}[/tex] = ne[tex]\mu _{e}[/tex] +pe[tex]\mu _{h}[/tex]     (1)

substituting all given values in eqn (1):

[tex]2.8\times 10^{4} = 2.9\times 10^{22}\times 1.6 \times 10^{-19}\times 0.14 + p\times1.6 \times 10^{-19}\times 0.023[/tex]

The cocentration of holes is:

[tex]p = 7.432\times 10^{24} m^{-3}[/tex]

Answer:

δ₂ = 15.07 mm

Explanation:

Given :

When the leading edge, [tex]x_{1}[/tex] is 2.2 m, then boundary layer thickness,δ₁ = 10 mm = 0.01 m

[tex]x_{2}[/tex] = 5 m

Now we know that for a laminar flow, the boundary layer thickness is

δ = [tex]\frac{5.x}{\sqrt{Re_{x}}}[/tex] -------(1)

and Reyonlds number, Re is

               [tex]Re = \frac{\rho .v.x}{\mu }[/tex]------(2)

where ρ is density

           v is velocity

           x is distance from the leading edge

           μ is dynamic viscosity

from (1) and (2), we get

δ∝[tex]x^{1/2}[/tex]

Therefore,

[tex]\frac{\delta _{1}}{x_{1}^{1/2}}= \frac{\delta _{2}}{x_{2}^{1/2}}[/tex]

[tex]\frac{10}{2.2^{1/2}}= \frac{\delta _{2}}{5^{1/2}}[/tex]

δ₂ = 15.07 mm

Therefore, boundary layer thickness is 15.07 mm when the leading edge is 5 m.

Answer:

Four rules that will control or eliminate pump cavitation are:

Explanation:

With reference to the above respective rules:

Answer:

a. true

Explanation:

Answer:

Explanation:

k_max = 26.9 w/mk

  k_min  =  22.33 w/mk

Explanation:

a) the maximum thermal conductivity is given as

K_MAX = k_m v_m + k_p v_p

where k_m is thermal conductvitiy of metal

k_p is thermal conductvitiy of carbide

v_m = proportion of metal in the cement = 0.15

v_p = proportion of carbide in the cement = 0.85

[tex]K_MAX = k_m v_m + k_p v_p[/tex]

            = 66*0.15 + 20*0.85

           k_max = 26.9 w/mk

b) the minimum thermal conductivity is given as

[tex]k_min = \frac{ k_{carbide} *k_{metal}}{k_{metal} v_{carbide} +k_{carbide} v_{metal}}[/tex]

          = \frac{20*66}{20*0.15 +66*0.85}

        k_min  = 22.33 w/mk

Answer:

Volumetric flow rate = 0.4773 m³/s

Mass flow rate = 477.3 kg/s

It will take 286.38 seconds to fill a tank with measurements 5 m x 6 m x 20 m

Explanation:

Given:

Diameter of the pipe through which the water is flowing = 450 mm

Radius = Diameter/2

Thus, Radius of the pipe = 225 mm

The conversion of mm into m is shown below:

1 mm = 10⁻³ m

Radius of the pipe = 225×10⁻³ m

The area of the cross-section = π×r²

So, Area of the pipe = π×/(225×10⁻³)² m² = 0.1591 m²

Also, Given : The water flowing rate = 3 m/s

Volumetric flow rate is defined as the amount of flow of the fluid in 1 sec.

[tex]Volumetric\ flow= \frac {Volume\ passed}{Time taken}[/tex]

This, can be written as Velocity of the fluid from the cross-section area of the pipe.

Q = A×v

Where,

Q is Volumetric flow rate

A is are though which the fluid is flowing

v is the velocity of the fluid

So,

Q = 0.1591 m²×3 m/s = 0.4773 m³/s

Mass flow rate is defined as the mass of the fluid passes per unit time.

[tex]\dot {m}= \frac {Mass\ passed}{Time taken}[/tex]

The formula in terms of density can be written as:

[tex]Density=\frac{Mass}{Volume}[/tex]  

So, Mass:

[tex]Mass= Density \times {Volume}[/tex]

Dividing both side by time, we get:

[tex]\dot {m}= Density \times {Q}[/tex]

Where,

[tex]\dot {m}[/tex] is the mass flow rate

Q is Volumetric flow rate

Density of water = 1000 kg/m³

Thus, Mass flow rate:

[tex]\dot {m}= 1000 \times {0.4773} Kgs^{-1}[/tex]

Mass flow rate = 477.3 kg/s

The time taken to fill the volume of measurement 5 m× 6 m× 20 m can be calculated from the formula of volumetric flow rate as:

t= Q×V

So,

Volume of Cuboid = 600 m³

Time = 0.4773 m³/s × 600 m³ = 286.38 s

Answer:

a) reciprocating pump

b) rotary pump

c) linear pump

Explanation:

Positive displacement pump has enlarged  cavity on the suction side and decreasing cavity on the discharge side and in  positive displacement pump

the amount of fluid captured and inside and then discharged is same.

There are three type of positive displacement pump

a) reciprocating pump is the pump which two valve during suction outlet valve is closed and  for delivery the inlet valve is closed and pump is used for discharge

b) rotary pump fluid move with the help of rotary the rotation of rotary displaces water.

c) linear pump is the pump in which displacement is linear rope and chain pump is example of this type of pump.

Answer:0.1898 Pa/m

Explanation:

Given data

Diameter of Pipe[tex]\left ( D\right )=0.15m[/tex]

Velocity of water in pipe[tex]\left ( V\right )=15cm/s[/tex]

We know viscosity of water is[tex]\left (\mu\right )=8.90\times10^{-4}pa-s[/tex]

Pressure drop is given by hagen poiseuille equation

[tex]\Delta P=\frac{128\mu \L Q}{\pi D^4}[/tex]

We have asked pressure Drop per unit length i.e.

[tex]\frac{\Delta P}{L} =\frac{128\mu \ Q}{\pi D^4}[/tex]

Substituting Values

[tex]\frac{\Delta P}{L}=\frac{128\times8.90\times10^{-4}\times\pi \times\left ( 0.15^{3}\right )}{\pi\times 4 \times\left ( 0.15^{2}\right )}[/tex]

[tex]\frac{\Delta P}{L}[/tex]=0.1898 Pa/m

Answer:

Enthalpy almost doubles.

Explanation:

Argon

Cp = Specific heat at constant volume = 0.520 kJ/kgK

T₁ = Initial temperature = 75°C

T₂ = Final temperature = 35°C

Enthalpy

Δh = CpΔT

⇒Δh = Cp(T₂-T₁)

⇒Δh = 0.520×(35-75)

⇒Δh = -20.8 kJ/kg

Neon

Cp = Specific heat at constant volume = 1.03 kJ/kgK

T₁ = Initial temperature = 75°C

T₂ = Final temperature = 35°C

Δh = Cp(T₂-T₁)

⇒Δh = 1.03×(35-75)

⇒Δh = -41.2 kJ/kg

Enthalpy will change because Cp value is differrent.

Enthalpy almost doubles.

Answer:

d). a and c

Explanation:

According to Pascal's law, when force is applied to a fluid, the pressure will increase equally in all direction of the container. Pascal law says that the pressure is transmitted undiminised in all direction inside a closed container. And the pressure inside the closed container is constant when measured at the same height above the datum.

Hence option d is correct.

Answer:

d = 13 mm

d =  15.68 mm

Explanation:

Given data

force = 20000 N

stress = 150 N/mm²

strain = 0.0005

E = 207 GPa

Solution

we know stress = force / area

so 0.0005 = 20000 / area

area = [tex]\pi[/tex]/4 × d²

put the area in stress equation and find out d

d² = 4×force / [tex]\pi[/tex] ×stress

d² = 4× 20000 / [tex]\pi[/tex] ×150

d = [tex]\sqrt{ 4× 20000 / [tex]\pi[/tex] ×150}[/tex]

d = 13 mm

and now we know starin = stress / E

same like stress we find d here

d = [tex]\sqrt{ 4× 20000 / [tex]\pi[/tex] ×0.0005×207×10³ }[/tex]

so d =  15.68 mm

Answer:

a). d = 13 mm

b). d = 16 mm

Explanation:

a). Given :

  Force = 20000 N

  Maximum stress, σ = 150 N/[tex]mm^{2}[/tex]

Therefore, we know that that

σ = [tex]\frac{Force}{area}[/tex]

150 = \frac{Force}{\frac{pi}{4}\times d^{2}}

150 = \frac{20000}{\frac{pi}{4}\times d^{2}}

[tex]d^{2}[/tex] = 169.76

d = 13.02 mm

d [tex]\simeq[/tex] 13 mm

b). Given :

   Strain, ε =  0.0005

   Young Modulus, E =  207 GPa

                                   = 207[tex]\times[/tex][tex]10^{3}[/tex] MPa

Therefore we know that, Stress σ = E[tex]\times[/tex]ε

                                                         = 207[tex]\times[/tex][tex]10^{3}[/tex][tex]\times[/tex]0.0005

                                                         = 103.5 N/[tex]mm^{2}[/tex]

We know that  

σ = [tex]\frac{Force}{Area}[/tex]

103.5 = [tex]\frac{Force}{\frac{pi}{4}\times d^{2}}[/tex]

[tex]d^{2}[/tex] = 246.27

d = 15.69 mm

d [tex]\simeq[/tex]16 mm

Answer:32.4m/[tex]s^2[/tex]

Explanation:

Given data

[tex]radius\left ( r\right )[/tex]=0.4m

Intial angular velocity[tex]\left ( \omega_0\right )[/tex]=4rad/s

angular acceleration[tex]\left ( \alpha\right )[/tex]=5rad/[tex]s^2[/tex]

angular velocity after 1 sec

[tex]\omega[/tex]=[tex]\omega_0 [/tex]+[tex]\alpha\times\t[/tex]

[tex]\omega[/tex]=4+5[tex]\left ( 1\right )[/tex]

[tex]\omega[/tex]=9rad/s

Velocity of point on the outer surface of disc[tex]\left ( v\right )[/tex]=[tex]\omega_0\timesr[/tex]

v=[tex]9\times0.4[/tex] m/s=3.6m/s

Normal component of acceleration[tex]\left ( a_c\right )[/tex]=[tex]\frac{v^2}{r}[/tex]

[tex]a_c[/tex]=[tex]\frac{3.6\times3.6}{0.4}[/tex]=32.4m/[tex]s^2[/tex]

Answer Explanation:

ROTARY ACTUATOR: A rotary actuator is an actuator that produces a rotary motion. An actuator requires a control signal and a source of energy.the linear motion in one direction gives rise to rotation.

EXAMPLE OF ROTARY ACTUATOR: the most used rotary actuators are rack and pinion, vane and helical

HOW IT IS USED: an actuator requires a control signal and its energy sources are current, fluid pressure when it receives a control signal it responds by converting signal energy into mechanical motion

Answer:

1). Entropy can be defined as a measure of sytem's thermal energy per unit temperature unavailable for ding useful work.

In other words, we can say that its a measure of the degree of randomness of a defined system.

Entropy-Environment relation:

Entropy is the fundamental concept that applies to the environment, humans or the entire universe.

The Second law  of thermodynamics explains the environmental impact of entropy. Reversing a process requires work, so reversing environmental process takes energy. Environmental impacts are higher at higher entropies and harder to reverse. Entropic flows and entropy measures can be used to prioritize the impacts which need action.

Increase of Entropy Principle:

This principle states that the total change in entropy of a system with its enclosed adiabatic surrounding is always positive i.e., greater than or equal to zero.

Answer:

Answer is part d -736.88  psi

Explanation:

We know that for a bar subjected to pure torsion the shear stresses that are generated can be calculated using the following equation

[tex]\frac{T}{I_{P} } =\frac{t}{r}[/tex]....................(i)

Where

T is applied Torque

[tex]I_{P}[/tex] is the polar moment of inertia of the shaft

t is the shear stress at a distance 'r' from the center

r is the radial distance

Now in our case it is given in the question T =82.7 ft*lbs

converting T into inch*lbs we have T = 82.7 x 12 inch*lbs =992.4 inch*lbs

We also know that for a circular shaft polar moment of inertia is given by

[tex]I_{P}=\frac{\pi D^{4} }{32}[/tex]

[tex]I_{P}= \frac{\pi\ 1.9^{4} }{32} =1.2794 inch^{4}[/tex]

Since we are asked the maximum value of shearing stresses they occur at the surface thus r = D/2

Applying all these values in equation  i we get

[tex]\frac{992.4 inch*lbs}{1.2794 inch^{4} } \frac{1.9 inches}{2}[/tex] = t

Thus t = 736.88 psi

Answer:

The velocities in points A and B are 1.9 and 7.63 m/s respectively. The Pressure at point B is 28 Kpa.

Explanation:

Assuming the fluid to be incompressible we can apply for the continuity equation for fluids:

[tex]Aa.Va=Ab.Vb=Q[/tex]

Where A, V and Q are the areas, velocities and volume rate respectively. For section A and B the areas are:

[tex]Aa=\frac{pi.Da^2}{4}= \frac{\pi.(0.1m)^2}{4}=7.85*10^{-3}\ m^3[/tex]

[tex]Ab=\frac{pi.Db^2}{4}= \frac{\pi.(0.05m)^2}{4}=1.95*10^{-3}\ m^3[/tex]

Using the volume rate:

[tex]Va=\frac{Q}{Aa}=\frac{0.9m^3}{7.85*10^{-3}\ m^3} = 1.9\ m/s[/tex]

[tex]Vb = \frac{Q}{Ab}= \frac{0.9m^3}{1.96*10^{-3}\ m^3} = 7.63\ m/s[/tex]

Assuming no losses, the energy equation for fluids can be written as:

[tex]Pa+\frac{1}{2}pa.Va^2+pa.g.za=Pb+\frac{1}{2}pb.Vb^2+pb.g.zb[/tex]

Here P, V, p, z and g represent the pressure, velocities, height and gravity acceleration. Considering the zero height level at point A and solving for Pb:

[tex]Pb=Pa+\frac{1}{2}pa(Va^2-Vb^2)-pa.g.za[/tex]

Knowing the manometric pressure in point A of 70kPa, the height at point B of 1.5 meters, the density of water of 1000 kg/m^3 and the velocities calculated, the pressure at B results:

[tex]Pb = 70000Pa+ \frac{1}{2}*1000\ \frac{kg}{m^3}*((1.9m/s)^2 - (7.63m/s)^2) - 1000\frac{kg}{m^3}*9,81\frac{m}{s^2}*1.5m[/tex]

[tex]Pb = 70000\ Pa-27303\ Pa - 14715\ Pa[/tex]

[tex]Pb = 27,996\ Pa = 28\ kPa[/tex]

Answer:

Partial and Fully abandonment of well is a term used for oil well

Explanation:

Full Abandonment - This condition is depend on economics of the oil well. when production from oil well is come to that level when operating cost become higher than  operating income, then it is need to shut down the well fully to prevent further loss.

Partial Abandonment -  in this condition only the base part of the well is neglect permanently and from the upper portion of the well sidetracked well is  build to acquire new target.

Answer Explanation : The general principles for design for assembly (DFA) are,

STEPS TO MINIMIZE THE NUMBER OF PARTS

Answer:227.56 mm

Explanation:

Given data

Elastic modulus[tex]\left ( E\right )[/tex]= 117 GPa

Diameter[tex]\left ( d\right )[/tex]=3.6mm

force applied[tex]\left ( F\right )[/tex]=2460N

Area of cross-section[tex]\left ( A\right )[/tex]=[tex]\frac{\pi}{4}\times d^{2}[/tex]=10.18[tex]mm^{2}[/tex]

and change in length is given by

[tex]\Delta L[/tex]=[tex]\frac{FL}{AE}[/tex]

[tex]\Delta {0.47\times 10^{-3}}[/tex]=[tex]\frac{2460\times L}{10.180\times 117\times 10^{3}}[/tex]

L=[tex]0.47\times 10^{-3}\times 10.18\times 117\times 10^{3][/tex]

L=227.56 mm

Answer and Explanation :The universe means it includes everything, even the things which we can not see is an isolated system because universe has no surroundings. an isolated system does not exchange energy or matter with its surroundings.Sometime universe is treated as isolated system because it obtains lots of energy from the sun but the exchange of matter or energy with outside is almost zero.

Answer:

The given statement is true.

Explanation:

Answer:para comprar terreno por ejemplo

to buy land for example

Explanation: meter, centimeter

The answer is : True

Answer:

Critical Reynolds number is a number or the threshold or the limit at which the laminar flow changes to turbulent flow.

Explanation:

It is basically the ratio of inertial forces to viscous forces and helps to predict if the flow is laminar or turbulent.

from the experiments, for flow in a pipe of diameter D, critical Reynolds number=2300

For Laminar flow: Reynolds number is less than 2000

For transitional flow: Reynolds number is in between 2000-4000, the flow is unstable

For Turbulent flow: Reynolds number is greater than 3500

Reynolds number is different for different geometries

Answer:

The answer is a) True  

Explanation:

"Statically Indeterminate" means the number of unknowns you have exceed the number of available equations you can get from the static analysis, then the Static (equilibrium) analysis isn't enough to solve the problem.  

Tracing constitutive models help to know where a load or reaction is located, also what kind of support settlements are used. This way you will know how the deflection behaves and also the momentum and torques location depending on the method you decide to use to solve the Statically Indeterminate system.

Answer:

true.

Explanation:

but i am not 100% sure

Answer: True

Explanation: It is correct that during a cycle the energy of the system remains unchanged. Total energy consist of the initial energy and the final energy in a system and both remain equal in a system whether they are in cycle or not  ans also according to the law of conservation of energy ,total energy cannot be destroyed or created. Thus the while a cycle goes on energy will remain the same.

Answer:

Harmful effect associated with extraction of Aluminum, Gold and Copper are:

During the melting of aluminium there is a released of per fluorocarbon are more harmful than carbon dioxide in the environment as they increased the level of green house gases and cause global warming. The process of transforming raw material into the aluminium are much energy intensive.

Gold mining industries destroyed land scopes and increased the amount of toxic level in the environment and they also dump there toxic waste in the natural water bodies, which increased the level of water pollution in the environment.

Copper mining causes the health problems like asthma and problem in respiratory system because of the inhalation of silica dust. It also increased the level of sulfur diode in the environment which cause acid rain and destroyed various trees and buildings in the nature.

Answer:

[tex]K=C+273.15[/tex]

Explanation:

Kelvin's climbing represents the absolute temperature. Temperature is a measure of the molecular kinetic energy of translation. If the molecules move quickly, with the same energy as in the walls of the container, which makes us feel like "heat". If the molecules do not move, the temperature is zero. 0 K.

The Celsius scale has an artificial zero, defined in the solidification temperature of the water. It is very useful to talk about the weather, and about some simpler technical matters. But it is artificial.

Answer:

Explanation:

We know that Drag force[tex]F_D[/tex]

  [tex]F_D=\dfrac{1}{2}C_D\rho AV^2[/tex]

Where

             [tex]C_D[/tex] is the drag force constant.

                 A is the projected area.

                V is the velocity.

                ρ is the density of fluid.

Form the above expression of drag force we can say that drag force depends on the area .So We should need to take care of correct are before finding drag force on body.

Example:

 When we place our hand out of the window in a moving car ,we feel a force in the opposite direction and feel like some one trying to pull our hand .This pulling force is nothing but it is drag force.