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2 years ago

If an atom has 15 protons, 12 neutrons, and 17 electrons, what is the atom's electrical charge? A. -5 B. -2 C. +3 D. +5

Physics

1 answer:

Nimfa-mama [501]2 years ago

5 0

Answer:

B. -2

Explanation:

The total charge on an atom is the sum of all individual charges present in it. Therefore, the total charge on this atom is given by the following formula:

$q = (n_p)(q_p)+(n_e)(q_e)+(n_n)(q_n)$

where,

q = total charge on atom = ?

$n_p$ = no. of protons in the atom = 15

$n_e$ = no. of electrons in the atom = 17

$n_n$ = no. of neutrons in the atom = 12

$q_p$ = charge on proton = +1

$q_e$ = charge on electron = -1

$q_n$ = charge on neutron = 0

Therefore,

$q = (15)(1)+(17)(-1)+(12)(0)\\q=-2$

Hence the correct option is:

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A 0.2 kg hockey puck moving at 80 m/s is caught by a 40 kg goalie at rest. With what speed does the goalie slide on the slide?

Lady_Fox [76]

Answer:

V = 0.39 m/s

Explanation:

Given that,

Mass of hockey puck, m = 0.2 kg

Mass of goalie = 40 kg

Speed of hockey puck, v = 80 m/s

We need to find the speed with which the goalie slide on the slide. Let V be the speed. Using the conservation of momentum as follows :

$mv=(M+m)V\\\\V=\dfrac{mv}{M+m}\\\\V=\dfrac{0.2\times 80}{0.2+40}\\\\V=0.39\ m/s$

So, the required speed is 0.39 m/s.

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2 years ago

__ is the second most abundant element in Earth’s crust. It is found in ___, and ___; and in _ which is used to make pottery.

lianna [129]

Answer:

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Explanation:

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2 years ago

A 0.75μF capacitor is charged to 70 V . It is then connected in series with a 55Ω resistor and a 140 Ω resistor and allowed to d

Ipatiy [6.2K]

Answer:

Explanation:

Capacitor of 0.75μF, charged to 70V and connect in series with 55Ω and 140 Ω to discharge.

Energy dissipates in 55Ω resistor is given by V²/R

Since the 55ohms and 140ohms l discharge the capacitor fully, the voltage will be zero volts and this voltage will be shared by the resistor in ratio.

So for 55ohms, using voltage divider rule

V=R1/(R1+R2) ×Vt

V=55/(55+140) ×70

V=19.74Volts is across the 55ohms resistor.

Then, energy loss will be

E=V²/R

E=19.74²/55

E=7.09J

7.09J of heat is dissipated by the 55ohms resistor

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3 years ago

Your friend turns the volume up on their speaker system, so that the sound intensity is 4 times greater than it was beforehand.

erica [24]

Answer:

Explanation:

We know that intensity I = P/A where P = power and A = area through which the power passes through.

Now, let the initial intensity of the speaker be I₀ and its initial power be P₀. Since the intensity is increased by a factor of 4, the new intensity be I and new power be P.

So, I = P/A and I₀ = P₀/A

Now, if I = 4I₀,

P/A = 4P₀/A

P = 4P₀

Now, energy E = Pt, where t = time. So, P = E/t and P₀ = E₀/t

Substituting P and P₀ into the equation, we have

P = 4P₀

E/t = 4E₀/t

E = 4E₀

Since the energy is four times the initial energy, the energy output increases by a factor of 4.

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2 years ago

A freight train rolls along a track with considerable momentum. If it were to roll at the same speed but had twice as much mass,

fomenos

Answer:

The momentum would be doubled

Explanation:

The magnitude of the momentum of the freight train is given by:

$p=mv$

where

m is the mass of the train

v is its speed

In this problem, we have that the speed of the train is unchanged, while the mass of the train is doubled:

$m'=2m$

therefore, the new momentum is

$p'=m'v=(2m)v=2(mv)=2p$

so, the momentum has also doubled.

7 0

2 years ago