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3 years ago

What percent of Earth’s surface is covered by land?

Physics

2 answers:

Olin [163]3 years ago

5 0

75 percent for sure!

sveticcg [70]3 years ago

4 0

25%, water takes up 75% Of the earth (im need to give 20 words to let me submit the answer)

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Why can beta particles pass through materials more easily than alpha particles? (2 points)

never [62]

Beta particles are smaller

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3 years ago

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The nuclear power used for electricity is produced by

svet-max [94.6K]

Answer:

<h3>b.fission. </h3>

Explanation:

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2 years ago

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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

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

4 0

3 years ago

A 11 g plastic ball is moving to the left at 29 m/s. How much work must be done on the ball to cause it to move to the right at

Rasek [7]

Answer:

4.25 J

Explanation:

Given that

mass of plastic ball = 11 g

Mass of plastic ball = 0.011 kg

velocity of ball = 29 m/s

We know that from work power energy theorem

$W_{all}=Change\ in\ kinetic\ energy\ of\ system$

We know that kinetic energy of moving mass given as

$KE=\dfrac{1}{2}mv^2$

Now by pitting the values

$KE=\dfrac{1}{2}mv^2$

$KE=\dfrac{1}{2}\times 0.011\times 29^2$

KE= 4.25 J

So the work done on the ball is 4.25 J

8 0

3 years ago

How much does a 20 kg rock weigh on Earth where g = 9.8 m/s2?

pentagon [3]

Answer:

$\huge\boxed{196\:N}$

Explanation:

Mass and weight ain't the same thing. So, for calculating weight we would use Newton's 2nd Law of Motion i.e. Force = Mass × Acceleration.

According to question,

The mass is 20kg

Acceleration is 9.8 m/s^2

Putting the given values into the formula,

F = 20 × 9.8

F = 196N

So, the weight of the rock is 196 N

Hope it helps!<3

3 0

2 years ago