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erastovalidia [21]
3 years ago
13

A 20-mm-diameter steel bar is to be used as a torsion spring. If the torsional stress in the bar is not to exceed 110 MPa when o

ne end is twisted through an angle of 15°, what must be the length of the bar?
Engineering
1 answer:
ch4aika [34]3 years ago
5 0

Answer:

1.887 m

Explanation:

(15 *pi)/180

= 0.2618 rad

Polar moment

= Pi*d⁴/32

= (22/7*20⁴)/32

= 15707.96

Torque on shaft

= ((22/7)*20³*110)/16

= 172857.14

= 172.8nm

Shear modulus

G = 79.3

L = Gjθ/T

= 79.3x10⁹x(1.571*10^-8)x0.2618/172.8

= 1.887 m

The length of the bar is therefore 1.887 meters

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The sports car has a weight of 4900 lblb and center of gravity at GG. If it starts from rest it causes the rear wheels to slip a
Zinaida [17]

Answer:

2.27secs

Explanation:

The car will take 2.27secs to reach a speed of 10 ft/s.

Kindly go through the attached files for a step by step solution that will show you how the answer was gotten and the normal reaction of both the front and rear wheels.

3 0
3 years ago
1. What did observations between 1912 and 1917 show?_____
valentinak56 [21]

The following set of prompts is astronomy related.

1) It is to be noted that the observations between 1912 and 1917  revealed that the earth was millions of years old and cooled down from a once molten state.

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3) It is TRUE to state that between 1912 and 1922, astronomer Vesto Slipher at the Lowell Observatory in Arizona uncovered that the spectra of light from many of these celestial entities were systematically shifted to longer wavelengths, or redshifted. The objects referenced here were galaxies in the distance.

4)  The important discovery that Hubble and his assistant discovered about galaxies was that some nebulae were galaxies <u>expanding </u>beyond our own galaxies.

5) It means that the universe has been growing or expanding ever since the Big Bang.

6) By observing very distant objects, scientists can tell whether or not the universe is moving, growing, or shrinking. This concept is referred to as redshift.

7) In 1965, the American Radio Astronomers Arno Penzias and Robert Wilson inadvertently discovered Cosmic Microwave Background Radiation.

8) According to all recent observations and studies, the Universe has no center.

9) It is estimated the Universe is 13.8 Billion Years old.

10) According to the Big Bang Theory, the whole Universe existed within a bubble millions of times smaller than the size of a pinhead. It was hotter and denser than we could have imagined. Then it burst into flames. According to this belief, this explosion produced life as we know it. It should be highlighted that, while the hypothesis has been utilized to explain numerous scientific facts, it is still an unproven theory.

<h3>When did the study of astronomy begin?</h3>

The Assyro-Babylonians made the earliest written records of regular astronomical observations approximately 1000 BCE. Astronomers had built an extensive knowledge of the celestial bodies and documented their periodic movements in Mesopotamia, which is located in the southern section of modern-day Iraq.

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Learn more about astronomy:
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7 0
1 year ago
A metallic material with yield stress of 140 MPa and cross section of 300 mm x 100 mm, is subjected to a tensile force of 8.00 M
Readme [11.4K]

Answer:Yes,266.66 MPa

Explanation:

Given

Yield stress of material =140 MPa

Cross-section of 300\times 100 mm^2

Force(F)=8 MN

Therefore stress due to this Force(\sigma)

\sigma =\frac{F}{A}=\frac{8\times 10^6}{300\times 100\times 10^{-6}}

\sigma =266.66 \times 10^{6} Pa

\sigma =266.66 MPa

Since induced stress  is greater than Yield stress therefore Plastic deformation occurs

8 0
3 years ago
5. A typical paper clip weighs 0.59 g and consists of BCC iron. Calculate (a) the number of
marta [7]

Answer:

(a) 3.185*10^{21} cells

(b) 6.37*10^{21} atoms

Explanation:

(a)

Volume, V of unit cell

V=(2.866*10^{-8})^{3}=2.354*10^{-23}

Number of unit cells, N

N=\frac {W_{mat}}{V\rho_{mat}} Where W_{mat} is weight of material and \rho_{mat} is density of material

N=\frac{0.59}{7.87*(2.354*10^{-23}}=3.185*10^{21} cells

(b)

Number of atoms in paper clip

This is a product of number of unit cells and number of atoms per cell

Since iron has 2 atoms per cell

Number of atoms of iron=3.185*10^{21} cells*2 atoms/cell=6.37*10^{21} atoms

8 0
3 years ago
For some transformation having kinetics that obey the Avrami equation, the parameter n is known to have a value of 2. If, after
kotegsom [21]

This question is incomplete, the complete question is;

For some transformation having kinetics that obey the Avrami equation, the parameter n is known to have a value of 2. If, after 100 s, the reaction is 40% complete, how long (total time in seconds) will it take the transformation to go to 95% completion

y = 1 - exp( -ktⁿ )

Answer: the time required for 95% transformation is 242.17 s

Explanation:

First, we calculate the value of k which is the dependent variable in Avrami equation

y = 1 - exp( -ktⁿ )

exp( -ktⁿ ) = 1 - y

-ktⁿ = In( 1 - y )

k = - In( 1 - y ) / tⁿ

now given that; n = 2, y = 40% = 0.40, and t = 100 s

we substitute

k = - In( 1 - 0.40 ) / 100²

k = - In(0.60) / 10000

k = 0.5108 / 10000

k = 0.00005108 ≈ 5.108 × 10⁻⁵

Now calculate the time required for 95% transformation

tⁿ = - In( 1 - y ) / k

t = [- In( 1 - y ) / k ]^1/n

n = 2, y = 95% = 0.95 and k = 5.108 × 10⁻⁵

we substitute our values

t = [- In( 1 - 0.95 ) / 5.108 × 10⁻⁵ ]^1/2

t = [2.9957 / 5.108 × 10⁻⁵]^1/2

t = [ 58647.22 ]^1/2

t = 242.17 s

Therefore the time required for 95% transformation is 242.17 s

8 0
3 years ago
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