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3 years ago

I hope some one can help me!

1 answer:

7 0

Given that:
μ = 36
<span>σ = 3
</span>
<span>Standardize x to z = (x - μ) / σ </span>
<span>P( 39 < x < 42) = P[( 39 - 36) / 3 < Z < ( 42 - 36) / 3] </span>
<span>P( 1 < Z < 2) = P( x < 2) - P( x < 1)
= 0.9772 - 0.8413
= 0.1359 </span>

<span>(0.1359)(30)
= 4.0777
= 4 days</span>

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Name the force which is responsible for revolution of moon around the earth

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Answer:

<em>Gravitational</em><em> force</em>

Explanation:

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2 years ago

A spherical steel ball bearing has a diameter of 2.540 cm at 20.00°C. (Assume the coefficient of linear expansion for steel is 1

shusha [124]

Answer:

(a) 2.542 cm

(b) 272.7°C

Explanation:

diameter, d = 2.540 cm

T1 = 20°C

α = 11 x 10^-6 /°C

(a) Let d' be the diameter.

T2 = 87°C

Use he formula for the areal expansion

A' = A ( 1 + βΔT)

where, β is the coefficient of areal expansion and ΔT is teh rise in temperature, A' be the area at high temperature and A be the area at low temperature.

β = 2 α = 2 x 11 x 106-6 = 22 x 10^-6 /°C

So,

$\frac{\pi D'^{2}}{4}=\frac{\pi D^{2}}{4}\left ( 1+\beta \Delta T \right )$

D'^2 = 2.54^2 ( 1 + 22 x 10^-6 x 67)

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(b) Let the change in temperature is ΔT.

Use the formula for the volumetric expansion

ΔV = V x γ x ΔT

Where, γ = 3 x α = 3 x 11 x 10^-6 = 33 x 10^-6 /°C

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3 years ago

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3 years ago

A 3000-kg crane is supporting a 10,000-kg crate. The crane pivots about point A and is at rest pressed against a support at B. (

Maru [420]

The answers are physically and mathematically reasonable, since both have the <em>same</em> order of magnitude of the <em>external</em> forces shown in the figure.

<h3 /><h3>Procedure - Determination of forces acting on a rigid body</h3>

Let be a system at equilibrium, which mathematically is represented by the following formulas:

$\Sigma F = 0$ (1)

$\Sigma M = 0$ (2)

<h3>a) Force acting on the crane at point A</h3>

We construct equations around points A and B by Newton's Laws and D'Alembert Principle:

<h3>Point A</h3>

$\Sigma M = F_{B}\cdot (1\,m)-(3000\,kgf)\cdot (2\,m)-(10000\,kgf)\cdot (6\,m) = 0$ (3)

<h3 /><h3>Point B</h3>

$\Sigma M = -F_{A,x}\cdot (1\,m) - (3000\,kgf)\cdot (2\,m)-(10000\,kgf)\cdot (6\,m) = 0$ (4)

<h3 /><h3>Entire system</h3>

$\Sigma F_{x} = F_{A,x} + F_{B} = 0$ (5)

$\Sigma F_{y} = F_{A,y} -3000\,kgf-10000\,kgf = 0$ (6)

The solution of the <em>entire</em> system is: $F_{A,x} = -66000\,kgf$ , $F_{B} = 66000\,kgf$ and $F_{A,y} = 13000\,kgf$ .

The magnitude of the force acting on the crane at point A is determined by the Pythagorean theorem:

$F_{A} = \sqrt{(-66000\,kgf)^{2}+(13000\,kgf)^{2}}$

$F_{A} \approx 67268.120\,kgf$

The force acting on the crane at point A has a magnitude of approximately 67268.128 kilograms-force. $\blacksquare$

<h3>b) The force acting on the crane at point B</h3>

The force acting on the crane at point B has a magnitude of approximately 66000 kilograms-force. $\blacksquare$

<h3>c) Order of Magnitude sense-making</h3>

The answers of parts (a) and (b) have an order of magnitude of $10^{3}$ , the same order of magnitude of the external forces shown in the figure. Hence, those answers are physically and mathematically reasonable.

<h3>Remark</h3>

Figure is missing. The statement is incomplete. Complete statement is presented below:

<em>A 3000 kilograms-force is supporting a 10000 kilograms-force crate. The crane pivots about point A and is at rest pressed against a support at B. </em>

<em>(a)</em><em> FInd the force acting on the crane at point A. </em>

<em>(b)</em><em> Find the force acting on the crane at point B. </em>

<em>(c)</em><em> Use order of magnitude sense-making to determine the reasonableness of your answers to parts (a) and (b). Hint: consider how the lever arm to the crate is much different than that to other points. </em>

To learn more on rigid bodies, we kindly invite to check this verified question: brainly.com/question/7031958