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3 years ago

2. Human Impact on the Environment

1 answer:

8 0

Burning fossil fuels emits a number of air pollutants that are harmful to both the environment and public health. Sulfur dioxide (SO2) emissions, primarily the result of burning coal, contribute to acid rain and the formation of harmful particulate matter.

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If an object 18 millimeters high is placed 12 millimeters from a diverging lens and the image is formed 4 millimeters in front o

Svetach [21]

C.
18 / x = 12 / 4
12x = 72
x = 6mm

6 0

3 years ago

what is the force of gravity attraction between an object with a mass of 0.5 kg and another object has a mass of 0.33 kg and a d

elena55 [62]

Answer:

$from \: newton \: law \: of \: gravitation \\ F = \frac{GMm}{ {r}^{2} } \\ G = 6.67 \times {10}^{ - 11} \\ M = 0.5 \: kg \\ m = 0.33 \: kg \\ r = 0.002 \: m \\ substitute \\ F = \frac{(6.67 \times {10}^{ - 11}) \times (0.5) \times (0.33)) }{ {(0.002)}^{2} } \\ = 2.75 \times {10}^{ - 6} N$

4 0

3 years ago

What is the average speed of a plane that flies 7,200 km in 9 hours?

Mnenie [13.5K]

First of all, the formula for speed is;
Speed=distance/time
From the question, you have;
distance=7,200km
Time=9 hours
So that will be;
Speed=7200/9
When divided, you will have;
Speed=800
The unit for speed is km/hr or m/s. So that will be;
Speed=800km/hr
Hope that helped, have a nice day

6 0

3 years ago

Consider a vortex filament of strength Γ in the shape of a closed circular loop of radius R. Consider also a straight line throu

Sedbober [7]

Answer:

$\vec{V} = \frac{\Gamma}{2R}\vec{A}$

Explanation:

We define our values according to the text,

R= Radius

$\vec{V} =$ Velocity

$\Gamma =$ Strenght of the vortex filament

From this and in a vectorial way we express an elemental lenght of this filmaent as $\vec{dl}$ . So,

$\vec{dl}x\vec{r} = R*dl*\vec{A}$

Where $\vec{A}$ imply a vector acting perpendicular to both vectors.

Applying Biot-Savart law, we have,

$\vec{V} =\frac{\Gamma}{4\pi}\int\frac{\vec{dl}x\vec{r}}{r^3}$

Substituting the preoviusly equation obtained,

$\vec{V} = \frac{\Gamma}{4\pi}\int\frac{R*dl*\vec{A}}{R^3}$

$\vec{V} = \frac{\Gamma}{4\pi R^2}\int^{2\pi R}_0 dl*\vec{A}$

$\vec{V} = \frac{\Gamma(2\pi R \vec{A})}{4\pi R^2}$

So we can express the velocity induced is,

$\vec{V} = \frac{\Gamma}{2R}\vec{A}$

6 0

3 years ago

Which condition is required for Coulomb's law to hold true?

AleksAgata [21]

The correct answer is:
Point charges must be in a vacuum.

In fact, the usual form for of the Coulomb's law is:
 $F= \frac{1}{4 \pi \epsilon_0} \frac{q_1 q_2}{r^2}$
where
 $\epsilon_0$ is the permittivity of free space
q1 and q2 are the two charges
q is the separation between the two charges

However, this formula is valid only if the charges are in vacuum. If they are in a material medium, the law is modified as follows:
 $F= \frac{1}{4 \pi \epsilon_0 \epsilon_r} \frac{q_1 q_2}{r^2}$
where $\epsilon_r$ is the relative permittivity, which takes into account the dielectric effects of the material.

7 0

2 years ago