A stone weighing 0.7 kilograms rolls down the inclined plane from position B to position A. Position A is located at sea level.

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

Do you have to keep citing the same source

emmasim [6.3K]

I don't think so as long as you make it apparent that the information comes the same source. So citing over and over again is unnecessary as long as it's clear that the information is from the same website or source. If you can't make it clear that they are from the same website source, it would a safe choice to continue to cite to avoid allegations of plagiarism.

4 0

3 years ago

Jessica jogs on a path that is 25 km long to get to the park that is south of the jogging path if it takes just a cut 2.5 hours

Vinil7 [7]

Answer:

10km/h

Explanation:

25÷2.5=10

speed = distance/time

velocity is a magnitude and needs a direction which wasnt provided so its basically the same as the speed

8 0

3 years ago

The ph of an acidic substance ia between what values on the ph scale

aalyn [17]

0 - 6 is acidic

7 is neutral

8 - 14 is basic

7 0

3 years ago

A student uses 150 N to push a block of wood up a ramp at constant velocity of 2.6m/s. What is his power output?

11Alexandr11 [23.1K]

Answer:

P= 390 W

Explanation:

In physics, power is the rate of doing work or of transferring heat, i.e. the amount of energy transferred or converted per unit time. Work is a force F applied over a distance x. Matemathicaly it means

P = dW/dt ≈ d(F * x)/dt = xdF/dt + Fdx/dt. If force is constant dF/dt=0 so P=F dx/dt = P*v, where v is velocity, the rate of distance per unit time.

We have force and velocity. Newton is unit of Kg*m/s2, hence

P= 150 kgm/s2 * 2.6 m/s =390 Kgm2/s3 = 390 W, where W is Watts and is an unit of power

8 0

3 years ago