To solve this problem it is necessary to apply the concepts related to the principle of superposition and constructive interference, that is to say everything that refers to an overlap of two or more equal frequency waves, which when interfering create a new pattern of waves of greater intensity (amplitude) whose cusp is the antinode.
Mathematically its definition can be given as:

Where
d = Width of the slit
Angle between the beam and the source
m = Order (any integer) which represent the number of repetition of the spectrum, at this case 1 (maximum respect the wavelength)
Since the point of the theta angle for which the diffraction becomes maximum will be when it is worth one then we have to:


Applying the given relation of frequency, speed and wavelength then we will have that the frequency would be:

Here the velocity is equal to the speed of light and the wavelength to the value previously found.


Therefore the smallest microwave frequency for which only the central maximum occurs is 1.5Ghz
Answer: Tension = 53.6N
Explanation:
Given that
Height h = 1 m
Time t = 1.7 s.
Mass m = 5.1 kg
From the equation of the motion we can get the acceleration of the elevator:
h = X0+ V0t + at2/2;
Th elevator starts from rest with a constant upward acceleration. Initial velocity Vo = 0, also Xo = 0; thus
a = 2h/t2 = 2 × 1/1.7^2
a = 0.69 m/s2.
Then we can find the tension in the cord by using the formula
T = mg + ma
= 5.1 (9.8 + 0.69)
= 5.1 × 10.5
= 53.6N
I think it’s a because it the only reasonable answer
Answer:
the angular acceleration of the gate is approximately 1.61 
Explanation:
Recall the formula that connects the net torque with the moment of inertia of a rotating object about its axis of rotation, and the angular acceleration (similar to Newton's second law with net force, mass, and linear acceleration):

In our case, both forces contribute to the same direction of torque, so we can add their torques up and get the net torque on the gate:

Now we use this value to obtain the angular acceleration by using the given moment of inertia of the rotating gate:

Cannot be determined, I need more information.