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3 years ago

If an atom has seven electrons how many are in the second shell?

Physics

2 answers:

Ostrovityanka [42]3 years ago

6 0

5 electrons because first shell can only have two electrons and second can hold up until 8

jeyben [28]3 years ago

4 0

If it had seven electrons then we know that the first energy lever has to have two and no more and so it would be 5 as you will only have 5 left. if you had more then 8 then there would be three but these not so your fine!! 5 electrons on other shell

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What is the distance from the crest to the equilibrium of a wave called? A. amplitude B. period C. frequency D. phase

Goryan [66]

its the first one. A.

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3 years ago

Read 2 more answers

An electric current of 200 A is passed through a stainless steel wire having a radius R of 0.001268 m. The wire is L = 0.91 m lo

denis23 [38]

Answer:

The value is $T_m = 435.2 \ K$

Explanation:

From the question we are told that

The current is $I = 200 \ A$

The radius is $R = 0.001268 \ m$

The length of the wire is $L = 0.91 \ m$ \

The resistance is $R = 0.126 \ \Omega$

The outer surface temperature is $T _o = 422.1 \ K$

The average thermal conductivity is $\sigma = 22.5 W/mK$

Generally the heat generated in the stainless steel wire is mathematically represented as

$Q = \frac{Power}{ \pi r^2L}$

$Q = \frac{I^2 R}{ \pi r^2L}$

=> $Q = \frac{200^2 * 0.126}{3.142 * (0.001268)^2 * 0.91}$

=> $Q = 1.096*10^{9}\ W/m^3$

Generally the middle temperature is mathematically represented as

$T_m = T_o + \frac{Q * r^2 }{ 6 * \sigma }$

$T_m = 422.1 + \frac{1.096*10^{-9} * 0.001268^2}{6 * 22.5}$

$T_m = 435.2 \ K$

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3 years ago

A high-jumper, having just cleared the bar, lands on an air mattress and comes to rest. Had she landed directly on the hard grou

Hoochie [10]

Answer:

e. the air mattress exerts the same impulse, but a smaller net avg force, on the high-jumper than hard-ground.

Explanation:

This is according to the Newton's second law and energy conservation that the force exerted by the hard-ground is more than the force exerted by the mattress.

The hard ground stops the moving mass by its sudden reaction in the opposite direction of impact force whereas the mattress takes a longer time to stop the motion of same mass in a longer time leading to lesser average reaction force.

Mathematical expression for the Newton's second law of motion is given as:

$F=\frac{dp}{dt}$ ............................................(1)

where:

dp = change in momentum

dt = time taken to change the momentum

We know, momentum:

$p=m.v$

Now, equation (1) becomes:

$F=\frac{d(m.v)}{dt}$

∵mass is constant at speeds v << c (speed of light)

$\therefore F=m.\frac{dv}{dt}$

and, $\frac{dv}{dt} =a$

where: a = acceleration

$\Rightarrow F=m.a$

also

$F\propto \frac{1}{dt}$

so, more the time, lesser the force.

& Impulse:

$I=F.dt$

$I=m.a.dt$

$I=m.\frac{dv}{dt}.dt$

$I=m.dv=dp$

∵Initial velocity and final velocity(=0), of a certain mass is same irrespective of the stopping method.

So, the impulse in both the cases will be same.

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madreJ [45]

Answer:

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Explanation:

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OlgaM077 [116]

Answer:

Explanation:

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