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3 years ago

How is varnished timber shaped and cut?

1 answer:

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You can paint over varnished wood as long as you use the right materials and painting process. The best paint to use is a water-based acrylic one. If you're using an oil-based paint only use an oil-based primer, not an acrylic one

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Stone has been used as a building material since ancient times because of its compressive strength, which is the __________.

Doss [256]

Complete Question:

Stone has been used as a building material since ancient times because of its compressive strength, which is the?

Group of answer choices

A. ability to support pressure without breaking.

B. ability to press down and become solidly fixed in the ground.

C. relative weight of a block of stone to its size.

D. force a block exerts on the blocks around it.

Answer:

A. ability to support pressure without breaking.

Explanation:

Stone has been used as a building material since ancient times because of its compressive strength, which is the ability to support pressure without breaking.

Compressive strength can be defined as the ability of a structural element or particular material to withstand an applied, which is aimed at reducing the size of the structural element.

Simply stated, it is the ability of a structural element or material to withstand an applied load without deflections, fracture or having any crack.

In this context, a stone possesses the ability to resist or withstand compression loads.

Some examples of other materials or structural elements having good compressive strength are steel, bones, concrete etc. The standard unit of measurement of the compressive strength of a material is Mega Pascal (MPa) or pound-force per square inch (psi) in the United States of America.

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4 years ago

A 25 kVA transformer has an iron loss of 200 W and a full-load copper loss of 350 W. Calculate the transformer efficiency for th

Oksanka [162]

Answer:

a. 97.32 percent

b. 97.92 percent

c. 95.91 percent

Explanation:

given parameters

apparent power, S = 25 kVA

Iron Loss, Piron = 200 W

copper Loss at full load, P cufl = 350 W

let the transformer efficiency at full load be E

let the real power be P out

at full load and 0.8 power factor

P out = Scos∅

= 25 x 10³ x 0.8

=20000 W or 20 kW

efficiency at full load is

E = (P out)/(P out + P iron + P cufl) x 100%

= (20000)/(20000 + 200 + 350) x 100%

= 97.32%

at 70% of full load at unity power factor of 1

Pout = 70% x Scos∅

= 0.7 x 25 x 10³ x 1

= 17,500W or 17.5kW

copper loss at 70% full load

P cu0.7fl = (70%)² x 350

= (0.7)² x 350

= 171.5 W

Iron loss remain the same, P iron = 200 W

Efficiency of transformer at 70% of full load

E = (P out0.7)/(P out0.7 + P iron + P cufl0.7) x 100%

= (17500)/(17500 + 200 + 171.5) x 100%

= 97.92%

at 40% of full load at a power factor of 0.6

P out = 40% x Scos∅

= 0.4 x 25 x 10³ x 0.6

= 6000 W or 6 kW

copper loss at 40% full load

P cu0.7fl = (40%)² x 350

= (0.4)² x 350

= 56 W

Iron loss remain the same, P iron = 200 W

Efficiency of transformer at 40% of full load

E = (P out0.4)/(P out0.4 + P iron + P cu0.4) x 100%

= (6000)/(6000 + 200 + 350) x 100%

= 95.91%

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3 years ago

Fluids at rest possess no flow energy. a)- True b)- False

gtnhenbr [62]

Answer:

True.

Explanation:

According the engineering flow they don not possess flow energy when they are in rest.

When they are in motion they show a translation energy.

The features if fluids may be different according the variables of pressure and temperature.

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3 years ago

You are an employee of Crewdson, Inc. Under the new policy, if you arrive to work late one morning, you will be required to

EastWind [94]

Answer:

C.leave work late that evening

Explanation:

As I'm the Employee of Crrewdson, Inc.

since I came late for work in the morning, because of the late train

As per the company's new policy, everyone should have to complete there work hours duration.

so I can't explain that situation to my Manager.

Therefore I had to work late that evening for completion of my work hours duration for that day.

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3 years ago

An escalator handles a steady load of 26 people per minute in elevating them from the first to the second floor through a vertic

photoshop1234 [79]

Answer:

$\eta = 70.711\,\%$

Explanation:

The power needed to make the escalator working is obtained by means of the Work-Energy Theorem:

$\dot W = \dot U_{g}$

$\dot W = \dot n \cdot m_{p}\cdot g \cdot \Delta y$

$\dot W = \left(26\,\frac{persons}{min}\right)\cdot (124\,lbm)\cdot \left(32.174\,\frac{ft}{s^{2}}\right)\cdot \left(\frac{1\,lbf}{32.174\,\frac{lbm\cdot ft}{s^{2}} } \right)\cdot (27.5\,ft)$

$\dot W = 88660\,\frac{lbf\cdot ft}{min}\,\left(2.687\,hp\right)$

The mechanical efficiency of the escalator is:

$\eta = \frac{2.687\,hp}{3.8\,hp}\times 100\,\%$

$\eta = 70.711\,\%$

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3 years ago