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4 years ago

Why do historians continue to gather historical evidence for even well-known events?

Engineering

2 answers:

Soloha48 [4]4 years ago

7 0

Answer:

lol

Explanation:

Dahasolnce [82]4 years ago

7 0

THE Answer: So They Find Out What Eles Happens With The Event And See What It Caueses.

Explanation:

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What are the reasons why fine grained of alkali igneous rocks can not be used in cement

Luden [163]

Fine grained of alkali igneous rocks cannot be used in cement because of the volume expansion caused by the Alkali-silica reaction, fine-grained igneous rocks cannot be used as aggregates in cement.

<h3>What does fine grained mean in an igneous rock?</h3>

Extrusive igneous rocks have a fine-grained or aphanitic texture, with grains that are too small to see without a magnifying glass. The fine-grained texture suggests that the rapidly cooling lava did not have enough time to form large crystals. A petrographic microscope can be used to examine these tiny crystals.

The texture of an igneous rock (fine-grained vs coarse-grained) is determined by the rate at which the melt cools: slow cooling produces large crystals, while fast cooling produces small crystals.

The chemical reaction that occurs in both alkali cations and hydroxyl ions in the pore solution of hydrated cement paste and certain reactive silica phases present in concrete aggregates is known as the alkali-silica reaction (ASR).

Learn more about cement on:

brainly.com/question/14323034

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8 0

2 years ago

Uses of P-N junction

Lubov Fominskaja [6]

Answer:

Explanation:

Two that come to mind:

a semiconductor diode is essentially a PN junction
a transistor is made of two pn junctions.

4 0

3 years ago

A paper clip is made of wire 0.75 mm in diameter. If the original material from which the wire is made is a rod 25 mm in diamete

Bas_tet [7]

Answer:

True strain = 3.7704

Explanation:

Strain is the measure an object that is stretched or deformed. This occurs when a force is applied to an object. Strain deals mostly with the change in length of the object. Strain = Δ L /L = Change in Length over the original Length:

Volume Constancy :

ΔL/L0=A0/ΔA=(D0/ ΔD)=(25mm/0.75mm)^2

ΔL/L0=44.4

Engineering strain:

Engineering strain =ΔL-L0/L0=ΔL/L0-1

Engineering strain =44.4-1=43.4

True strain, ε=In(ΔL/L0)=In(43.4)=3.7704

Note that strain has no unit, so the True strain = 3.7704

8 0

4 years ago

a cubical box 20-cm on a side is contructed from 1.2 cm thick concrete panels. A 100-W light bulb is sealed inside the box. What

Flura [38]

Answer:

Temperature on the inside ofthe box

Explanation:

The power of the light bulb is the rate of heat conduction of the bulb, $dq/dt = 100 W$

The thickness of the wall, L = 1.2 cm = 0.012m

Length of the cube's side, x = 20cm = 0.2 m

The area of the cubical box, A = 6x²

A = 6 * 0.2² = 6 * 0.04

A = 0.24 m²

Temperature of the surrounding, $T_0 = 20^0 C = 273 + 20 = 293 K$

Temperature of the inside of the box, $T_{in} = ?$

Coefficient of thermal conductivity, k = 0.8 W/m-K

The formula for the rate of heat conduction is given by:

$dq/dt = \frac{kA(T_{in} - T_0)}{L} \\\\100 = \frac{0.8*0.24(T_{in} - 293)}{0.012}\\\\T_{in} - 293 = \frac{100 * 0.012}{0.8*0.24} \\\\T_{in} - 293 = 6.25\\\\T_{in} = 293 + 6.25\\\\T_{in} = 299.25 K\\\\T_{in} = 299.25 - 273\\\\T_{in} = 26.25^0 C$

5 0

4 years ago

1. You have a Co-Cr alloy with Young's Modulus: 645 MPa, Poisson ratio 0.28, and yield strength 501 MPa for that alloy when used

bazaltina [42]

Answer:

F_x = 100,200 N

x' = 21.321 cm ... Length

y' =0.7825 cm

z' = 1.565 cm

A' = ( 0.783 x 1.565 ) cm

Explanation:

Given:

- The Modulus of Elasticity E = 645 MPa

- The poisson ratio v = 0.28

- The Yield Strength Y = 501 MPa

- The Length along x-direction x = 12 cm

- The length along y-direction y = 1 cm

- The length along z--direction z = 2 cm

Find:

The maximum tensile load that can be applied in the longitudinal direction of the bar without inducing plastic deformation. b. The length and cross-sectional area of the bar at its tensile elastic limit.

Solution:

- The Tensile forces within the limit of proportionality is given as:

F_i = б_i*A_jk

- A maximum tensile Force F_x along x direction can be given as:

F_x = Y*A_yz

F_x = 501*( 0.01*0.02)*10^6

F_x = 100,200 N

- The corresponding strains in x, y and z direction due to F_x are:

ξ_x = Y / E

ξ_x = 501 / 645 = 0.7767

ξ_y = ξ_z = -v*Y / E

ξ_y = ξ_z = -0.28*501 / 645 = - 0.2175

- The corresponding change in lengths at tensile elastic stress are:

Δx = x*ξ_x = 12*0.7767 = 9.321 cm

Δy = y*ξ_y = - 1*0.2175 = -0.2175 cm

Δz = z*ξ_z = - 2*0.2175 = -0.435 cm

- The final lengths are:

x' = x + Δx = 12 + 9.321 = 21.321 cm

y' = y + Δy = 1 - 0.2175 = 0.7825 cm

z' = z + Δz = 2 - 0.435 = 1.565 cm

3 0

4 years ago