Answer:
eksqijakojqnozjzbw.wlisjaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
Explanation:
A) 750 m
First of all, let's find the wavelength of the microwave. We have
is the frequency
is the speed of light
So the wavelength of the beam is

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

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

and so, the diameter is

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

So the area is

And since the power is

The average intensity is

Answer:
Time required by boat 1 for the round trip is less than that of boat 2.
Hence, boat 1 wins.
Explanation:
Case 1: Boat 1
Speed of boat = 
time = 
While going to another end
time = 
time = 
time = 1 hour
While going back,
time = 
time = 
time = 1 hour
Total time taken by boat 1 is,
Total time by boat 1 = 1 hour + 1 hour = 2 hour
Total time by boat 1 = 2 hour
Total time taken by boat 1 for the round trip is 2 hour.
Case 2: Boat 2
Speed of boat = 
time = 
While going to another end
time = 
time = 
time = 2 hour
While going back,
time = 
time = 
time = 0.66 hour
Total time taken by boat 2 is,
Total time by boat 1 = 2 hour + 0.66 hour
Total time by boat 1 = 2.66 hour
Total time taken by boat 2 for the round trip is 2.66 hour.
Time required by boat 1 for the round trip is less than that of boat 2.
Hence, boat 1 wins.
I believe that the answer to this would be B
Hope this helped