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3 years ago

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How do scientists determine the number of neutrons in an isotope of an atom? A. They find the number of protons. B. They divide

the atomic mass by two. C. They add the number of electrons and protons. D. They subtract the atomic number from the atomic mass.

2 answers:

nekit [7.7K]3 years ago

7 0

D is the answer by the looks of it sry if wrong

Aleks04 [339]3 years ago

5 0

'D' would do the job ... When you subtract the protons from the mass,
what you have left is neutrons. (The electrons can be ignored. It takes
around 1840 electrons ! to add the mass of a single proton or neutron !)

I don't know it for a fact, but I'd be surprised if the process is really that
simple. I mean, it starts out with knowing the atomic mass, and then
knowing the number of protons in the nucleus. Each of those is a
whole complex problem in itself.

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3 years ago

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What is the (magnitude of the) centripetal acceleration (as a multiple of g=9.8~\mathrm{m/s^2}g=9.8 m/s 2 ) towards the Eart

Wittaler [7]

Answer:

The centripetal acceleration as a multiple of $g=9.8 m/s^{2}$ is $1.020x10^{-3}m/s^{2}$

Explanation:

The centripetal acceleration is defined as:

$a = \frac{v^{2}}{r}$ (1)

Where v is the velocity and r is the radius

Since the person is standing in the Earth surfaces, their velocity will be the same of the Earth. That one can be determined by means of the orbital velocity:

$v = \frac{2 \pi r}{T}$ (2)

Where r is the radius and T is the period.

For this case the person is standing at a latitude $71.9^{\circ}$ . Remember that the latitude is given from the equator. The configuration of this system is shown in the image below.

It is necessary to use the radius at the latitude given. That radius can be found by means of trigonometric.

$\cos \theta = \frac{adjacent}{hypotenuse}$

$\cos \theta = \frac{r_{71.9^{\circ}}}{r_{e}}$ (3)

Where $r_{71.9^{\circ}}$ is the radius at the latitude of $71.9^{\circ}$ and $r_{e}$ is the radius at the equator ( $6.37x10^{6}m$ ).

$r_{71.9^{\circ}}$ can be isolated from equation 3:

$r_{71.9^{\circ}} = r_{e} \cos \theta$ (4)

$r_{71.9^{\circ}} = (6.37x10^{6}m) \cos (71.9^{\circ})$

$r_{71.9^{\circ}} = 1.97x10^{6} m$

Then, equation 2 can be used

$v = \frac{2 \pi (1.97x10^{6} m)}{24h}$

Notice that the period is the time that the Earth takes to give a complete revolution (24 hours), this period will be expressed in seconds for a better representation of the velocity.

$T = 24h . \frac{3600s}{1h}$ ⇒ $84600s$

$v = \frac{2 \pi (1.97x10^{6} m)}{84600s}$

$v = 146.31m/s$

Finally, equation 1 can be used:

$a = \frac{(146.31m/s)^{2}}{(1.97x10^{6}m)}$

$a = 0.010m/s^{2}$

Hence, the centripetal acceleration is $0.010m/s^{2}$

To given the centripetal acceleration as a multiple of $g=9.8 m/s^{2}$ it is gotten:

$\frac{0.010m/s^{2}}{9.8 m/s^{2}} = 1.020x10^{-3}m/s^{2}$

6 0

3 years ago

The surface charge density on an infinite charged plane is −1.70 x 10^−6 C/m^2 . A proton is shot straight away from the plane a

goldfiish [28.3K]

Answer:

Acceleration of proton will be $-9.197\times 10^{12}m/sec^2$

Explanation:

We have given surface charge density of an infinite charged plate $\sigma = -1.70\times 10^{-6}C/m^2$

Electric field due to infinite sheet charge is given by $E=\frac{\sigma }{2\epsilon _0}=\frac{-1.7\times 10^{-6}}{2\times 8.85\times10^{-12}}=-0.096\times 10^6=-9.6\times 10^4N/C$

Charge in proton is given by $e=1.6\times 10^{-19}C$

So force on proton $F=qE=1.6\times 10^{-19}\times -9.6\times 10^4=-15.36\times 10^{-15}N$

Mass of proton $m=1.67\times 10^{-27}kg$

According to newtons second law force F = mass × acceleration

So $-15.36\times10^{-15}=1.67\times 10^{-27}a$

$a=-9.197\times 10^{12}m/sec^2$

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3 years ago

What is atmospheric pressure ? How can we calculate it?

oksian1 [2.3K]

Answer:

Atmospheric pressure is the pressure exerted by the weight of the atmosphere.

Atmospheric Pressure = density of Mercury X acceleration due to gravity X height of column of the mercury

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3 years ago

What evidence is there that sound Travels through gases

anygoal [31]

Answer:

solid

Explanation:

because the molecule of solid is farest than gas

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