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Orlov [11]
3 years ago
13

A 2.1-mF capacitor is discharged through a 4.0-kΩ resistor. How long will it take for the capacitor to lose half its initial sto

red energy?
(A) 5.82 s
(B) 2.91 s
(C) 0.660 s
(D) 4.20 s
(E) 8.40 s
Physics
1 answer:
Harrizon [31]3 years ago
4 0

Answer:

the answer is a)5.82s

Explanation:

Hello!

The first thing we must understand to solve this exercise is that a capacitor has the following characteristic function

V=(Vo)e^{-t/RC}

where

Vo=initial voltage

V=voltage in an instant of time

t=time

R=resistance=4000Ω

C=capacitance=2.1-mF=0.0021F

we must consider that the final voltage is half of the initial voltage so we deduce the following equation

V=Vo/2

Now we replace in the initial equation, and start an algebraic process to find t

\frac{Vo}{2} =(Vo)e^{-t/RC}\\0.5=e^{-t/RC}\\ln(0.5)=ln(e^{-t/RC})\\ln(0.5)=\frac{-t}{RC} \\t=-(RC)ln0.5

finally with the equation ready, we use the resistance and capacitance values ​​to find the time value

t=-(4000)(0.0021)ln(0.5)=5.82s

the answer is a)5.82s

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eduard

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d

Explanation:

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9 = 0  +  0    + 1/2 a ( 3)^2

9 = 4.5 a

a = 2 m/s^2

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When atoms collide with the walls of their container,_____ is exerted
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3 years ago
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On an icy road, a 1100 kg car moving at 55 km/h strikes a 480 kg truck moving in the same direction at 37 km/h . The pair is soo
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Answer:

Speed of the wreckage = 49.29 km/hr

Explanation:

This question is solved simply by using the conservation of momentum law.

The momentum of the three moving bodies are calculated below:

Momentum of Car 1 : 1100 * 55 = 60500 kg.km/hr

Momentum of Truck : 480 * 37 = 17760 kg.km/hr

Momentum of Car 2 : 1300 * 49 = 63700 kg.km/hr

Total mass of all three vehicles: 1100 + 480 + 1300 = 2880 kg

The final momentum equals the initial momentum if it is conserved. Thus we have the following equation:

Final Momentum = Initial Momentum

Final Velocity * Total mass = Momentum of all three vehicles combined

Final Velocity * 2880 = 60500 + 17760 + 63700

Final Velocity = 49.29 km/hr

7 0
4 years ago
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what will be the focal lenght of a combined lens made by contact of two lenses of power +3D and -2D.​
4vir4ik [10]
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  • P_2=-2D

\\ \bull\tt\dashrightarrow P=P_1+P_2

\\ \bull\tt\dashrightarrow P=+3D-2D=+1D

Now

\\ \bull\tt\dashrightarrow f=\dfrac{1}{P}

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3 0
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<u>Answer</u>

Yes, the car reaches the door before the gate closes.

<u>Explanation</u>

The time taken by the car to reach at the door.

Time = distance / time

        = 22/13

          = 1.6923 seconds

Time taken by the door to close up to the height of the car.

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t = 28.537 seconds

Answer: Yes, the car reaches the door before the gate closes.


3 0
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