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3 years ago

Select all that apply.

Physics

2 answers:

oee [108]3 years ago

8 0

B and D are the correct answers

Ira Lisetskai [31]3 years ago

7 0

A = false, it will take 0.031 cal to raise 1g Au 1degree while it will take 0.033 cal to raise 1g Hg 1 degree so, although Au will heat up faster, it will not be discernably faster so...
b = true
c = false, Au density > Hg
d = true

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A radar for tracking aircraft broadcasts a 12 GHz microwave beam from a 2.0-m-diameter circular radar antenna. From a wave persp

NISA [10]

A) 750 m

First of all, let's find the wavelength of the microwave. We have

$f=12GHz=12\cdot 10^9 Hz$ is the frequency

$c=3.0\cdot 10^8 m/s$ is the speed of light

So the wavelength of the beam is

$\lambda=\frac{c}{f}=\frac{3\cdot 10^8 m/s}{12\cdot 10^9 Hz}=0.025 m$

Now we can use the formula of the single-slit diffraction to find the radius of aperture of the beam:

$y=\frac{m\lambda D}{a}$

where

m = 1 since we are interested only in the central fringe

D = 30 km = 30,000 m

a = 2.0 m is the aperture of the antenna (which corresponds to the width of the slit)

Substituting, we find

$y=\frac{(1)(0.025 m)(30000 m)}{2.0 m}=375 m$

and so, the diameter is

$d=2y = 750 m$

B) 0.23 W/m^2

First we calculate the area of the surface of the microwave at a distance of 30 km. Since the diameter of the circle is 750 m, the radius is

$r=\frac{750 m}{2}=375 m$

So the area is

$A=\pi r^2 = \pi (375 m)^2=4.42\cdot 10^5 m^2$

And since the power is

$P=100 kW = 1\cdot 10^5 W$

The average intensity is

$I=\frac{P}{A}=\frac{1\cdot 10^5 W}{4.42\cdot 10^5 m^2}=0.23 W/m^2$

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3 years ago

Greg has decided to incorporate earth science into his teaching with snowflakes. As he walks around the room, he notices that ma

Nastasia [14]

A. By asking them to go outside and study real snowflakes.

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3 years ago

A crane is holding up a concrete block with a steel cable. What is a contact force that is acting on the block?

miv72 [106K]

Answer:

Tension.

Explanation:

I just had this question so I hope it sort of helps.

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3 years ago

A cart being pulled with 30N through a 2 m hallway over two seconds. How does it have the greatest power exerted on it

Lapatulllka [165]

Answer:

Power = 30 [watts]

Explanation:

Initia data:

F = force = 30[N]

d = displacement = 2 [m]

By definition we know that work is equal to the product of force by the distance displaced

Therefore:

W = F * d = 30 * 2

W = 60 [J]

And power is defined as the amount of work done in a given time interval

time = t = 2 [sec]

Power = W / t

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Power = 30 [W]

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3 years ago

What row of the periodic table does this element belong?

sladkih [1.3K]

Answer:

Group 18

Explanation:

This element has a full octet, therefore it is a noble gas, being in period 18. (I think its Argon if you need that too)

Hope that helps

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3 years ago