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zimovet [89]
3 years ago
10

Direct current, DC, flows in a _________ direction while alternating current, AC, the direction of flow ___________. A) single,

is unidirectional B) constant, periodically reverses C) opposite direction, is multiple D) periodically reversing, is constant
Physics
2 answers:
Mademuasel [1]3 years ago
5 0

Answer:

B

Explanation:

I just had it on USA Test Prep

kramer3 years ago
4 0
The flow of Direct current (DC) is constant and flows in one direction. Most digital electronics make use of DC. Alternating current (AC) periodically flows in reverse and is mostly used to deliver power to houses, buildings and the like. With that alone, you can already rule out A, C and D. 

The answer would then be B. constant, periodically reversing. 
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Now find the components NxNxN_x and NyNyN_y of N⃗ N→N_vec in the tilted coordinate system of Part B. Express your answer in term
MArishka [77]

Answer:

N_{y} =NcosФ,

N_{x} =-Nsin Ф

Explanation:

Now find the components NxNxN_x and NyNyN_y of N⃗ N→N_vec in the tilted coordinate system of Part B. Express your answer in terms of the length of the vector NNN and the angle θθtheta, with the components separated by a comma.

Vectors are quantities that  have both magnitude and direction while scalar quantities have only magnitude but no direction.

This a vector quantity

from the diagram the horizontal component of the length of the vector will be

N_{y} =NcosФ

the vertical component will be

N_{x} =-Nsin Ф

this is in the opposite direction because the x can be extrapolated to the negative axis

7 0
3 years ago
Read 2 more answers
A commuter train passes a passenger platform at a constant speed of 40.4 m/s. The train horn is sounded at its characteristic fr
mihalych1998 [28]

(a) -83.6 Hz

Due to the Doppler effect, the frequency of the sound of the train horn appears shifted to the observer at rest, according to the formula:

f' = (\frac{v}{v\pm v_s})f

where

f' is the apparent frequency

v = 343 m/s is the speed of sound

v_s is the velocity of the source of the sound (positive if the source is moving away from the observer, negative if it is moving towards the observer)

f is the original frequency of the sound

Here we have

f = 350 Hz

When the train is approaching, we have

v_s = -40.4 m/s

So the frequency heard by the observer on the platform is

f' = (\frac{343 m/s}{343 m/s - 40.4 m/s})(350 Hz)=396.7 Hz

When the train has passed the platform, we have

v_s = +40.4 m/s

So the frequency heard by the observer on the platform is

f' = (\frac{343 m/s}{343 m/s + 40.4 m/s})(350 Hz)=313.1 Hz

Therefore the overall shift in frequency is

\Delta f = 313.1 Hz - 396.7 Hz = -83.6 Hz

And the negative sign means the frequency has decreased.

(b) 0.865 m

The wavelength and the frequency of a wave are related by the equation

v=\lambda f

where

v is the speed of the wave

\lambda is the wavelength

f is the frequency

When the train is approaching the platform, we have

v = 343 m/s (speed of sound)

f = f' = 396.7 Hz (apparent frequency)

Therefore the wavelength detected by a person on the platform is

\lambda' = \frac{v}{f'}=\frac{343 m/s}{396.7 Hz}=0.865m

5 0
3 years ago
Which of the following statements does NOT accurately describe the Berlin Airlift?
Karo-lina-s [1.5K]

The Berlin Airlift is best described as the aircraft used to delivered needed food and supplies to the city of Berlin through the air because all other routes were blocked by the Soviet Union.

<h3>What is Berlin Airlift?</h3>

The Berlin airlift was a 1940s military operation that supplied West Berlin with food and other vital goods by air after the Soviet Union blockaded the city.

Thus, the Berlin Airlift is best described as the aircraft used to delivered needed food and supplies to the city of Berlin through the air because all other routes were blocked by the Soviet Union.

Learn more about Berlin Airlift here: brainly.com/question/1104371

#SPJ1

8 0
2 years ago
A 120-kg roller coaster cart is being tested on a new track, and a crash-test dummy is loaded into itThe roller coaster starts f
Black_prince [1.1K]

Answer:

a) variation of the energy is equal to the work of the friction force

b) W = Em_{f} -Em₀ ,  c) he conservation of mechanical energy

Explanation:

a) In an analysis of this problem we can use the energy law, where at the moment the mechanical energy is started it is totally potential, and at the lowest point it is totally kinetic, we can suppose two possibilities, that the friction is zero and therefore by equalizing the energy we set the velocity at the lowest point.

 Another case is if the friction is different from zero and in this case the variation of the energy is equal to the work of the friction force, in value it will be lower than in the calculations.

b) the calluses that he would use are to hinder the worker's friction force and energy

          W = Em_{f} -Em₀

          N d = ½ m v² - m g (y₂-y₁)

          y₂-y₁ = 35 -10 = 25m

c) if there is no friction, the physical principle is the conservation of mechanical energy

 If there is friction, the principle is that the non-conservative work is equal to the variation of the energy

7 0
3 years ago
Calculate the kinetic energy of a car of mass 800kg moving at 100 kmph.
valentina_108 [34]

Answer:

KE = 308642.02469136 J

4 0
2 years ago
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