This is junior year english

Why a raw egg shell disolves when submerge in vineger

quester [9]

If you soak this egg shell in vinegar (which is about 4% acetic acid), you start a chemical reaction that dissolves the calcium carbonate shell. The acetic acid reacts with the calcium carbonate in the egg shell and releases carbon dioxide gas that you see as bubbles on the shell.

6 0

3 years ago

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A 175-kg roller coaster car starts from rest at the top of an 18.0-m hill and rolls down the hill, then up a second hill that ha

Anni [7]

Answer:

The work done by non-conservative forces on the car from the top of the first hill to the top of the second hill is 6574.75 joules.

Explanation:

By Principle of Energy Conservation and Work-Energy Theorem we present the equations that describe the situation of the roller coaster car on each top of the hill. Let consider that bottom has a height of zero meters.

From top of the first hill to the bottom

$m\cdot g \cdot h_{1} = \frac{1}{2}\cdot m\cdot v_{1}^{2} +W_{1, loss}$ (1)

From the bottom to the top of the second hill

$\frac{1}{2}\cdot m\cdot v_{1}^{2} = m\cdot g \cdot h_{2} + \frac{1}{2}\cdot m \cdot v_{2}^{2}+W_{2,loss}$ (2)

Where:

$m$ - Mass of the roller coaster car, in kilograms.

$v_{1}$ - Speed of the roller coaster car at the bottom between the two hills, in meters per second.

$g$ - Gravitational acceleration, in meters per square second.

$h_{1}$ - Height of the first top of the hill with respect to the bottom, in meters.

$W_{1, loss}$ - Work done by non-conservative forces on the car between the top of the first hill and the bottom, in joules.

$v_{2}$ - Speed of the roller coaster car at the top of the second hill, in meters per seconds.

$h_{2}$ - Height of the second top of the hill with respect to the bottom, in meters.

$W_{2, loss}$ - Work done by non-conservative forces on the car bewteen the bottom between the two hills and the top of the second hill, in joules.

By using (1) and (2), we reduce the system of equation into a sole expression:

$m\cdot g\cdot h_{1} = m\cdot g\cdot h_{2} + \frac{1}{2}\cdot m \cdot v_{2}^{2} + W_{loss}$ (3)

Where $W_{loss}$ is the work done by non-conservative forces on the car from the top of the first hill to the top of the second hill, in joules.

If we know that $m = 175\,kg$ , $g = 9.807\,\frac{m}{s^{2}}$ , $h_{1} = 18\,m$ , $h_{2} = 8\,m$ and $v_{2} = 11\,\frac{m}{s}$ , then the work done by non-conservative force is:

$W_{loss} = m\cdot\left[ g\cdot \left(h_{1}-h_{2}\right)-\frac{1}{2}\cdot v_{2}^{2} \right]$

$W_{loss} = 6574.75\,J$

The work done by non-conservative forces on the car from the top of the first hill to the top of the second hill is 6574.75 joules.

8 0

3 years ago

Theorem: there is no smallest positive rational number.theorem: there is no smallest positive rational number. a proof by contra

matrenka [14]

Assume there is a smallest rational integer that has the following form: a/b

Then observe that we can define a/(b+1), which is strictly less than a/b because its divisor is bigger and is rational because it is the product of two numbers. Due to the contradiction created by our original claims that a/b is the smallest rational number that is possible, we might conclude that there is no such thing as the smallest rational number.

There can therefore be no smallest rational number because we may always define a smaller rational number than the one we now possess.

<h3>What is Rational number ?</h3>

Any number that can be expressed as a ratio is considered reasonable. It is therefore possible to represent it as a fraction when the numerator and denominator are both full numbers.

Learn more about Rational number here:

brainly.com/question/12088221

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5 0

1 year ago

How does an increase in greenhouse gases in the atmosphere cause an increase in global temperature?

daser333 [38]

Answer:

<h2>Greenhouse gases absorb and emit radiation and less heat dissipates to space</h2>

Explanation:

when heat is trapped it is conducted to the trapped area and gradually heats up its surrounding

8 0

3 years ago

A mountaintop is a height y above the level ground. A woman measures the angle of elevation of the

Kamila [148]

Refer to the diagram shown below.
We want to find y in terms of d, φ and θ.

By definition,
$tan (\theta) = \frac{y}{x} \\\\ tan( \phi) = \frac{y}{x-d}$

Therefore
y = x tan(θ) (1)
y = (x - d) tan(φ) (2)

Equate (1) and (2).
$(x - d) \, tan(\phi) = x \, tan(\theta) \\ x[tan(\phi) - tan(\theta)] = d \, tan(\phi) \\ x= \frac{d tan(\phi)}{tan(\phi)-tan(\theta)}$

From (1), obtain the required expression for y.

Answer:
$y= \frac{d \, tan(\phi) \, tan(\theta)}{tan(\phi)-tan(\theta)}$

7 0

3 years ago