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3 years ago

Why are objects that fall near earths surface rarely in free fall?

1 answer:

8 0

"Free fall" means that gravity is the ONLY force acting on the object. If there's air resistance, then it isn't free-fall.

Objects that fall near earths surface are ALWAYS falling through air, unless they're inside some kind of a vacuum chamber with all the air removed from it.

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Holes are being steadily injected into a region of n-type silicon (connected to other devices, the details of which are not impo

Tems11 [23]

Complete Question

The complete question is shown on the first uploaded image

Answer:

The value is $J_n = -0.864 \ A/cm^2$

Explanation:

Generally for an n-type semiconductor the current density is mathematically represented as

$J_n = -q * d_p * \frac{d p_{n_o}}{d_w}$

Here $p_{n_o}$ is mathematically represented as

$p_{n_o} = \frac{n_i^2}{n_d}$

=> $p_{n_o} = \frac{(1.5*10^{10})^2}{10^{16}}$

=> $p_{n_o} = 2.25 *10^{4} \ cm^{-3}$

$d p_{n_o} = P_n0 - p_{n_o}$

From the diagram $P_n0 = 10^8 * p_{n_o}$

=> $P_n0 = 10^8 * (2.25 *10^{4} )$

$d p_{n_o} = 10^8 * (2.25 *10^{4} ) - 2.25 *10^{4}$

$d p_{n_o} = 2.25 *10^{12} cm^{-3}$

So from $J_n = -q * d_p * \frac{d p_{n_o}}{d_w}$

substitute

$1.60 *10^{-19} \ C$ for q and $w_2 =50 nm = 50*10^{-9} m = 5*10^{-6} cm$

and from the diagram $w_1 =0 \ cm$

$J_n = -1.60 *10^{-19} *12 * \frac{2.25 *10^{12} }{ 5*10^{-6} - 0 }$

$J_n = -0.864 \ A/cm^2$

6 0

3 years ago

Which muscle disorder does donna’s doctor diagnose? donna is suffering from leg pain in which the calf muscles contract involunt

Kay [80]

Donna's doctor must have diagnosed her with muscle cramps. With the given symptoms above, it is likely that she is experiencing muscle cramps. Muscle cramps most likely happen when the individual experiencing it is lack of fluid intake, causing the muscles to tighten causing pain and for the muscle to contract involuntarily.

7 0

3 years ago

Read 2 more answers

An insect 5.00 mm tall is placed 20.0 cm to the left of a thin planoconvex lens. The left surface of this lens is flat, the righ

jenyasd209 [6]

Answer:

a) i = -9.63 cm , h ’= .0.24075 cm erect

b) i = 259.74 cm ,

Explanation:

For this exercise let's start by finding the focal length of the lens

1 / f = (n-1) (1 / R₁ - 1 / R₂)

1 / f = (1.70 -1)) 1 / ∞ - 1/13)

1 / f = 0.0538

f = - 18.57 cm

Now we can use the constructor equation

1 / f = 1 / o + 1 / i

1 / i = 1 / f - 1 / o

1 / i = -1 / 18.57 -1/20

1 / i = -0.1038 cm

I = -9.63 cm

For the height of the

image let's use magnification

m = h '/ h = - i / o

h ’= -h i / o

h ’= - 0.5 (-9.63) / 20

h ’= .0.24075 cm

b) we invert the lens

The focal length is

1 / f = (1.70 -1) (1/13 - 1 / int)

1 / f = 0.0538

f = 18.57 cm

1 / i = 1 / f -1 / o

1 / I = 1 / 18.57 - 1/20

1 / I = 3.85 10-3

i = 259.74 cm

h ’= - 0.5 259.74 / 20

h ’= 6.4935 cm

7 0

3 years ago

AM Radio Waves

Komok [63]

Answer:

Explanation:

6 0

3 years ago

Read 2 more answers

A sound wave from a police siren has an intensity of 100.0 W/m² at a certain point; a second sound wave from a nearby ambulance

Irina18 [472]

The sound level of the sound wave due to the ambulance is 140.

<h3>What do you mean by sound?</h3>

In terms of physics, the sound is a vibration that travels through a transmission medium like a gas, liquid, or solid as an acoustic wave. Sound is the reception of these waves and the brain's perception of them in terms of human physiology and psychology. Only acoustic waves with frequencies between roughly 20 Hz and 20 kHz, or the audio frequency range, can cause a human to have an auditory sensation. These are sound waves with wavelengths ranging from 17 meters (56 ft) to 1.7 millimeters in the air at atmospheric pressure (0.67 in). Ultrasounds are sound waves with a frequency higher than 20 kHz that are inaudible to humans. Infrasound refers to sound frequencies below 20 Hz. Animals of different species have different hearing ranges.

To learn more about sound, Visit:

brainly.com/question/9349349

#SPJ4

3 0

2 years ago