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3 years ago

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An inductance L, resistance R, and ideal battery of emf are wired in series. A switch in the circuit is closed at time t = 0, at

which time the current is zero. At any later time t the emf of the inductor is given by:The question is aksing the emf of inducotr not resistor, the answer is D. Could anyone explain it to me? thank youA) (1 – e–Lt/R)B) e–Lt/RC) (1 + e–Rt/L)D) e–Rt/LE) (1 – e–Rt/L)

2 answers:

Kay [80]3 years ago

3 0

Explanation:

After some time t the current does not passing through the circuit

=>so the back emf is zero

=>here the inductor opposes decay of the circuit

- Ldi/dt = Ri

di/dt = - R/Li

di/i = - R/Ldt

now we applying the integration on both sides

log i=-R/Lt+C

here t=0=>i=io

Log io=C

=>Log i=-R/L*t + Log io

logi-Log io=-R/L*t

Log[i/io]=-R/L*t

i/io=e^-Rt/L

i=ioe^-Rt/L

the option D is correct

4vir4ik [10]3 years ago

3 0

Answer:

D) e–Rt/LE) (1 – e–Rt/L)

Explanation:

After some time t the current does not passing through the circuit

=>so the back emf is zero

=>here the inductor opposes decay of the circuit

-Ldi/dt=Ri

di/dt=-R/Li

di/i=-R/Ldt

now we applying the integration on both sides

log i=-R/Lt+C

here t=0=>i=io

Log io=C

=>Log i=-R/L×t+Log io

logi-Log io=-R/L×t

Log[i/io]=-R/L*t

i/io=e^-Rt/L

i=ioe^-Rt/L

the option D is correc

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Answer:

a) 5.64 C

b) 3.5*10¹⁹ protons

Explanation:

a)

Since the four metallic objects are identical, and total charge must be conserved, this means that after brought simultaneously into contact so that each touches the others, once separated, total charge must be the same than before being brought in contact.
But due they are identical, after charges were able to transfer freely between them, the four objects must have the same final charge, i.e. the fourth part of the total charge, as follows:

$Q_{n} = \frac{Q_{tot}}{4} = \frac{22.57C}{4} = 5.64 C (1)$

b)

This charge will be divided between n protons, since the charge is positive.
Since each proton carries a charge equal to the elementary charge e, which value is 1.6*10⁻¹⁹ C, we can find the number of protons in excess, doing the following calculation:
$n_{p} =\frac{Q_{n}}{e} = \frac{5.64C}{1.6e-19C} = 3.5 e19 C (2)$

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3 years ago

Find the pressure exerted by a force 8000 newton's on an area of 25m^2. Give your answer in newton's/n^2

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The pressure exerted by this force is equal to 320 $N/m^2$ .

<u>Given the following data:</u>

Force = 8000 Newton.

Area = 25 $m^2$ .

To calculate the pressure exerted by this force:

<h3>How to calculate pressure.</h3>

Mathematically, pressure is given by this formula:

$P=\frac{F}{A}$

<u>Where:</u>

P is the pressure.

F is the force.

A is the area.

Substituting the given parameters into the formula, we have:

$P = \frac{8000}{25}$

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3 years ago

Alicia está a punto de perder su bus. En un desesperado intento, corre a una velocidad constante de 5 m/s. Cuando está a 15 m de

pochemuha

Answer:

Si logra alcanzar el bus.

Explanation:

Para poder solucionar este problema debemos de tener en cuenta que Alicia corre a velocidad constante para poder alcanzar el bus. La formula de la cinematica que tiene en cuenta la velocidad constante es la siguiente:

$x_{f} = x_{o}+(v*t)$

donde:

Xf = Ubicacion del punto donde se encuentra el bus [m]

Xo = Ubicacion desde donde esta Alicia [m]

v = velocidad constante = 5 [m/s]

t = tiempo [s]

Xf - Xo = 15 [m]

15 = 5*t

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Ahora con el tiempo podemos encontrar la velocidad del bus por medio de la siguiente ecuacion de cinematica para la aceleracion constante:

$v_{f} = v_{i}+(a*t)$

donde:

Vf = velocidad del bus despues de los 3 [s]

Vi = velocidad inicial = 0

a = aceleracion = 0.5 [m/s^2]

Vf = 0 + (0.5*3)

Vf = 1.5 [m/s]

La velocidad del bus es menor que la velocidad de Alicia, por ende Alicia alcanzara el bus.

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3 years ago

Dylan has two cubes of iron. The larger cube has twice the mass of the smaller cube. He measures the smaller cube. Its mass is 2

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Density = mass/volume, volume = mass/density.
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3 years ago

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The maximum energy a bone can absorb without breaking is surprisingly small. For a healthy human of mass 60 kg60 kg, experimenta

netineya [11]

Answer:

<em>the maximum height a man can jump from and land rigidly upright on both feet without breaking his legs is 0.34 m</em>

<em></em>

Explanation:

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energy the bone can take without breaking = 200 J

If a healthy man jumps from a height 'h', he falls with an energy equal to the potential energy due to his initial height above the ground.

initial potential energy of the healthy man = mgh

where m = mass of the man

g = acceleration due to gravity = 9.81 m/s^2

h = the height above ground

==> PE = 60 x 9.81 x h = 588.6h

If we assume that all energy is absorbed in the leg bones in a rigid landing, then we can safely say that this calculated PE for a healthy man is equal to the energy his bone can absorb in the jump without breaking.

equating, we have

200 = 588.6h

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When people jump from a height, the sudden deceleration to zero can impact a big force on the leg bones, shattering them. If the time spent in decelerating to zero is increased, the overall force on the leg bones is reduced greatly.

<em>Bending the knees gradually on landing from a jump from a height, and then rolling increases the time spent decelerating, and reduces the impact force on the legs due to the landing</em>. If you observe carefully you will see that this is what professional stunts men and acrobats do when they jump from a height.

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3 years ago