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3 years ago

10

Stars combine Hydrogen to make Helium during nuclear fusion. Living things are made of heavier elements like Carbon, Oxygen, Iro

n, and Calcium. How did these elements form?

1 answer:

alex41 [277]3 years ago

8 0

They were formed in the nuclear<span> fusion reaction inside older </span><span>stars.

As a star burns, fusion reactions inside its core create heavier elements. Those materials are released when the star dies of old age in an explosion.</span>

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Diagnostic ultrasound of frequency 3.82 MHz is used to examine tumors in soft tissue. (a) What is the wavelength in air of such

maxonik [38]

Explanation:

It is given that,

Frequency of diagnostic ultrasound, f = 3.82 MHz = 3820 Hz

The speed of the sound in air, v = 343 m/s

(a) We need to find the wavelength in air of such a sound wave. Let it is given by λ₁

i.e. $\lambda=\dfrac{v}{\nu}$

$\lambda_1=\dfrac{343\ m/s}{3820\ Hz}$

$\lambda_1=0.089\ m$

(b) If the speed of sound in tissue is 1650 m/s .

$\lambda_2=\dfrac{v}{\nu}$

$\lambda_2=\dfrac{1650\ m/s}{3820\ Hz}$

$\lambda_2=0.43\ m$

Hence, this is the required solution.

7 0

3 years ago

A california condor is sitting on the top branch of a redwood tree and has a GPE of 12,100 J. If the condor has a mass of 8kg, w

DanielleElmas [232]

Answer:

william h. seward secured the purchase of alaska from:

Explanation:

3 0

3 years ago

Question 1 Gary is on the space shuttle. It takes off and lifts him to a height of 300 km above Earth's surface. a. How has Gary

balandron [24]

A) The mass is an intrinsic property of an object: it means it depends only on the properties of the object, so it does not depend on the location of the object. Therefore, Gary's mass at 300 km above Earth's surface is equal to his mass at the Earth's surface.

b) The weight of an object is given by
$W=mg$
where
m is the mass
$g= \frac{GM}{r^2}$ is the gravitational acceleration at the location of the object, with G being the gravitational constant, M the mass of the planet and r the distance of the object from the center of the planet.

At the Earth's surface, $g=9.81 m/s^2$ , so Gary's weight is
$W=mg=9.81 m$ (1)
where m is Gary's mass.

Then, we must calculate the value of g at 300 km above Earth's surface. the Earth's radius is
$R=6370 km$
So the distance of Gary from the Earth's center is
$r=R+h=6370 km+300 km =6670 km = 6.67 \cdot 10^6 m$

The Earth's mass is $M=5.97 \cdot 10^{24} kg$ , so the gravitational acceleration is
$g'=G \frac{M}{r^2}= (6.67 \cdot 10^{-11} m^3 kg^{-1} s^{-2} )\frac{5.97 \cdot 10^{24} kg}{(6.67 \cdot 10^6 m)^2}=8.95 m/s^2$

Therefore, Gary's weight at 300 km above Earth's surface is
$W' = mg' = 8.95 m$ (2)

If we compare (1) and (2), we find that Gary's weight has changed by
$\frac{W'}{W}= \frac{8.95 m}{9.81 m}=0.91$
So, Gary's weight at 300 km above Earth's surface is 91% of his weight at the surface.

6 0

3 years ago

Refrigerators are usually kept at about 5∘C, while room temperature is about 20∘C. If you were to take an "empty" sealed 2-liter

expeople1 [14]

Answer:

The volume will not contract to one fourth of the original.

Explanation:

Applying Charles's Law as:

$\frac {V_1}{T_1}=\frac {V_2}{T_2}$

Given ,

V₁ = ?

V₂ = 2 L

T₁ = 5 °C

T₂ = 20 °C

The conversion of T( °C) to T(K) is shown below:

T(K) = T( °C) + 273.15

So,

T₁ = (5 + 273.15) K = 278.15 K

T₂ = (20 + 273.15) K = 293.15 K

Using Charles law as:

$V_1=\frac {V_2}{T_2} \times {T_1}$

$V_1=\frac {2\ L}{293.15 K} \times {278.15 K}$

$V_1=1.8977 L$

Thus, the volume will not contract to one fourth of the original. (1/4 of 2 L is 0.5 L).

8 0

4 years ago

Define neuron and nerve<br>cell

san4es73 [151]

Answer: Hi!

A neuron is a basic working unit of the brain. Neurons are special cells designed to transfer information to other nerve, muscle, or gland cells. They are pretty cool - looking too! (A slightly irregular circular shape with branches reaching out from all sides.) A neuron is a nerve cell. Nerve cells are the way of communication in the nervous system.

Hope this helps!

3 0

3 years ago

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