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Ugo [173]
3 years ago
12

An electromagnetic wave is transporting energy in the negative y direction. At one point and one instant the magnetic field is i

n the positive x direction. The electric field at that point and instant is:
Why is (D) the answer? I thought it's (C)

a. positive y direction
b. negative y direction
c. positive z direction
d. negative z direction
Physics
1 answer:
natali 33 [55]3 years ago
4 0

Answer:. Option c

Explanation: the speed of an electromagnetic wave is simply the vector product of the magnetic field and the electric field.

The direction of the velocity is the direction of the electromagnetic wave.

The wave is already moving towards the negative y axis (-j) and the magnetic field is already pointing towards the positive x axis (i)

From cross product of unit vectors

i × j = k

i × k = - j

With the second identity, we can see that the electric field will be pointing towards the positive of the x axis (k).

Option c is validated

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A brick in the shape of a cube with sides 10 cm has a density of 2500 kg/m^3. What is its weight? a.) 250 N
Arisa [49]

Answer:

c.) 25 N

Explanation:

 We find the volume of the brick, knowing that the volume of a cube is given by the formula:

l=0,1 metros \\V=l^{3}\\V=(0,1\: \: m)^{3}=0,001\: \: m^{3}

being l the side of the cube, which in this case is 10 cm or 0,1 m. Now we find the mass of the object, knowing the density and the Volume of the cube:

m=V*d\\m=(0,001 \:\:m^{3})(2500 \: \: \frac{Kg}{m^{3}})=2,5 \:\: Kg

We find the weight by multiplying the mass of the object with the gravity constant.

W=m*g=(2.5 \:Kg)*(9,81 \:m/s^{2} )=24,5 N\approx25\: N

8 0
3 years ago
A. What did the neuron say to the muscle say? (Use your basic physiological knowledge, such as the function of
Romashka-Z-Leto [24]

Answer:

Somatic motor neurons originate in the central nervous system, project their axons to skeletal muscles (such as the muscles of the limbs, abdominal, and intercostal muscles), which are involved in locomotion.

Explanation:

Muscles move on commands from the brain. Single nerve cells in the spinal cord, called motor neurons, are the only way the brain connects to muscles. When a motor neuron inside the spinal cord fires, an impulse goes out from it to the muscles on a long, very thin extension of that single cell called an axon.

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Kara is writing a science-fiction story. In the story, Earth no longer experiences day and night.
Ludmilka [50]

Answer:

C. She should get the Earth spinning on its axis again.

Explanation:

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6 0
3 years ago
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Which of the following statements about comets is true? A. Comets rarely fall into an orbit around the Sun. They usually enter t
GREYUIT [131]
<h2>Right answer: Comets have very elliptical orbits that usually take them far beyond the orbit of Pluto, but also take them closer to the Sun than Earth</h2>

Comets are celestial bodies constituted by ice, dust and rocks that orbit around the Sun, after having been altered by the Oort cloud; following different trajectories that can be <u>highly eccentric elliptical</u><u> </u>(periodic trajectories), parabolic or hyperbolic.

One of the main characteristics of a comet is that it travels quite fast, on its way around the Sun and has a long tail. It should be noted that the tails of comets always go in the opposite direction to the Sun (due to the radiation pressure of sunlight).

Therefore, the correct option is C.

4 0
3 years ago
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Answer:

Distance of 400m.

Explanation:

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d = 200 + 200

d = 400 m

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2 years ago
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