The answer is: " **5 g / cm³** " .

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**Explanation: **

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Density = mass divided by volume ; or: "D = m / V " ;

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and is expressed as: "mass per unit volume" ;

The mass, "m", is expressed in units of "g" (grams) ; and

the volume, "V" is expressed in units of "cm³ " or "mL" ; ("cm³ ", in this case);

**{Note the exact conversion: " 1 cm³ = 1 mL " .} .**

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So, if: the mass, "m = 100 g" {given} ;

and the volume, " V = 20 cm³ " {given} ;

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Plug these values into the formula/equation to solve for the density, "D" ;

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D = m / V = (100 g) / (20 cm³)

= (100 ÷ 20) g / cm³ **= 5 g /cm³** .

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** The answer is:** " **5 g / cm³** " **.**

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**Answer:Dr. Hess' most significant contribution to the plate tectonic theory began in 1945 when he was the commander of the U.S.S. ... In the paper Hess described how hot magma would rise from under the crust at the Great Global Rift. When the magma cooled, it would expand and push the tectonic plates apart.**

**Explanation:**

**Answer:**

See attached document

**Explanation:**

Entire process for deriving the asked expression dV across the bridge as function of dP is illustrated in the attachment below.

The document gives a step-by step process for arriving at the expression. However, manipulation of algebraic equations is skipped for the conciseness of the document.

It also gives the expression for the case when all resistors have different nominal values.

**Answer:**

Plan B.

Because flexibility is best improved by stretching.

**Explanation:**

Improving and increasing flexibility is done by having stretching sessions daily which maintains and widens the range of motion in the joints and stretches muscles.