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3 years ago

Who is Rachel Carson and why is she important to environmentalism

1 answer:

5 0

Rachel Carson was an American marine biologist, who after the discovery of the effects of synthetic pesticides on the environment, became a conservationist.. She wrote a book called, <em>Silent Spring</em> which helped advance the worldwide environmental movement. Her book, <em>Silent Spring</em> expressed her feelings and thoughts on the environmental problems, including many problems with synthetic pesticides like DDT. <em />This then influenced a nationwide ban on many pesticides, including DDT. Her book lead to the inspiration of the grassroots movement and the creation of the U.S Environmental Protection Agency. Rachel Carson was also awarded the Presidential Medal of Freedom by Jimmy Carter.

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A convex mirror of focal length 34 cm forms an image of a soda bottle at a distance of 18 cm behind the mirror. The height of th

Mademuasel [1]

<h2>Answers:</h2>

In convex mirrors the focus is virtual and the focal distance is negative. This is how the reflected rays diverge and only their extensions are cut at a point on the main axis, resulting in a virtual image of the real object .

<h2 /><h2>a) Position of the soda bottle (the object) </h2><h2 />

The Mirror equation is:

$\frac{1}{f}=\frac{1}{u}+\frac{1}{v}$ (1)

Where:

$f$ is the focal distance

$u$ is the distance between the object and the mirror

$v$ is the distance between the image and the mirror

We already know the values of $f$ and $v$ , let's find $u$ from (1):

$u=\frac{v.f}{v-f}$ (2)

Taking into account the explanation at the beginign of this asnswer:

$f=-34cm$ and $v=-18cm$

The <u>negative signs</u> indicate the <u>focal distance</u> and the <u>distance between the image and the mirror are virtual </u>

Then:

$u=\frac{(-18cm)(-34cm)}{-18cm-(-34cm)}$

$u=38.25cm$ (3) >>>>Position of the soda bottle

<h2>b) magnification of the image </h2><h2 />

The magnification $m$ of the image is given by:

$m=-\frac{v}{u}$ (4)

$m=-\frac{(-18cm)}{38.25cm}$

$m=0.47$ (5)>>>the image is 0.47 smaller than the object

<h2>The fact that this value is positive means the image is upright </h2>

<h2>c) Describe the image </h2><h2 />

According to the explanations and results obtained in the prior answers, the correct option is 9:

<h2>The image is <u>virtual, upright, smaller</u> than the object </h2><h2 /><h2>d) Height of the soda bottle (object) </h2>

Another way to find the magnification is by the following formula:

$m=\frac{h_{i}}{h_{o}}$ (6)

Where:

$h_{i}$ is the image height

$h_{o}$ is the object height

We already know the values of $m$ and $h_{i}$ , let's find $h_{o}$ :

$h_{o}=\frac{h_{i}}{m}$ (7)

$h_{o}=\frac{6.8cm}{0.47}$

$h_{o}=14.46cm$ (8) >>>height of thesoda bottle

6 0

3 years ago

The height of a cone is increasing at a rate of 10 cm/sec and its radius is decreasing so that its volume remains constant. How

ki77a [65]

Answer:

dr/dt = -2 cm/s.

Explanation:

The volume of a cone is given by:

$V=\frac{1}{3} \pi r^{2}h$ (1)

r is the radius
h is the height

Let's take the derivative with respect to time in each side of (1).

$\frac{dV}{dt}=\frac{1}{3} \pi \frac{d}{dt}(r^{2}h)=\frac{1}{3} \pi \left(2r\frac{dr}{dt}h+r^{2}\frac{dh}{dt} \right)$ (2)

We know that:

dh/dt = 10 cm / s (rate increasing of height)
dV/dt = 0 (constant volume means no variation with respect of time)
r = 4 cm
h = 10 cm

We can calculate how fast is the radius changing using the above information.

$0=\frac{1}{3} \pi \left( 2\cdot 4\cdot \frac{dr}{dt} \cdot 10 + 4^{2}\cdot 10)\right$

Therefore dr/dt will be:

$\frac{dr}{dt}=-\frac{160}{80}=-2 cm/s$

The minus signs means that r is decreasing.

I hope it helps you!

6 0

3 years ago

Our Sun will eventually:

nasty-shy [4]

B. become a white dwarf star

It will swell, shed its layers, and become a white dwarf star.

I know the sun does not have enough mass to become a supernova or a black hole.

3 0

4 years ago

Read 2 more answers

Explain how sound travels through the air to observer

Harlamova29_29 [7]

Sample:
As soon as the lightning is seen, sound travels in the air for several kilometers until it eventually reaches the observer.

3 0

4 years ago

When unpolarized light is incident on a sheet of polarizing material with a transmission axis oriented vertically, what percenta

yulyashka [42]

Answer:

If the light were incident upon two polarizers at right angles, no light would get thru - thus each polarizer must block 50% of the light.

One polarizer would allow 50% of the light to pass.

4 0

2 years ago