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3 years ago

. Why are objects that fall near Earth's surface rarely in free fall?

Physics

2 answers:

gtnhenbr [62]3 years ago

8 0

Answer:

Objects that fall near Earth’s surface are rarely in free fall.

"Free fall" is the situation where the ONLY force on an object is

the force of gravity, and nothing else.

Objects near Earth's surface are almost always surrounded by air.

If they are falling, then the air is exerting forces on them, and they

are not in "free fall".

pls mark me brainliest

Explanation:

timurjin [86]3 years ago

6 0

Answer:

Air exerts forces that fall near Earth’s surface

Explanation:

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melisa1 [442]

The correct answer is transmission<<<<<<

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3 years ago

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

Shawn and his bike have a total mass of

Trava [24]

Answer:

Shawn's kinetic energy is 61.45 J.

Explanation:

Given;

Mass of the system is, $m=52.3\ kg$

Displacement of the bike is, $d=1.6\ km=1.6\times 1000=1600\ m$

Time taken is, $t=17.4\ min=17.4\times 60=1044\ s$

Let the constant velocity be $v$ .

For constant velocity, magnitude of velocity is given as distance by time.

Therefore, $v=\frac{d}{t}=\frac{1600}{1044}=1.533\ m/s$

Now, kinetic energy of a body is given as:

$KE=\frac{1}{2}mv^2$

Here, $m=52.3\ kg,\ v=1.533\ m/s$

$\therefore KE=\frac{1}{2}\times 52.3\times (1.533)^2\\KE=0.5\times 52.3\times 2.35\\KE=61.45\ J$

Therefore, Shawn's kinetic energy is 61.45 J.

3 0

3 years ago

If a 10kg block is at rest on a table and a 1200N force is applied in the eastward direction for 10 seconds, what is the acceler

gavmur [86]

Answer:

a = 120 m/s²

Explanation:

We apply Newton's second law in the x direction:

∑Fₓ = m*a Formula (1)

Known data

Where:

∑Fₓ: Algebraic sum of forces in the x direction

F: Force in Newtons (N)

m: mass (kg)

a: acceleration of the block (m/s²)

F = 1200N

m = 10 kg

Problem development

We replace the known data in formula (1)

1200 = 10*a

a = 1200/10

a = 120 m/s²

6 0

3 years ago

Why is Tycho Brahe often called “the greatest naked-eye astronomer” of all time?

riadik2000 [5.3K]

Answer:Explained Below

Explanation:

Tycho Brahe saw a super nova which inspired him to study astronomy.His observations are 5 times more accurate than other astronomers of his time and thus he was given a private island to study about astronomy .He made most accurate naked eye measurements ever.

So he can be said to be the "greatest naked eye astronomer of all time"

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3 years ago