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3 years ago

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1) An ac source of period T and maximum voltage V is connected to a single unknown ideal element that is either a resistor, and

inductor, or a capacitor. At time t = 0 the voltage is zero and increasing toward a maximum. At time t = T/4 the current in the unknown element is equal to zero and at time t = T/2 the current is I = -Imax (where Imax is the maximum current amplitude). What is the unknown element?

1 answer:

Lady_Fox [76]3 years ago

6 0

Answer: Capacitor

Explanation:

Given the following ;

At time, t = T/4 ; I = 0

At time, t = T/2 ; I = - Imax

Where T = period

We can confirm what the unknown element is by using the relation, such that the parameters satisfy the stated condition ;

Recall;

I = Iosin(wt + π/2) [for CAPACITOR]

w = 2π/T

At t = T/4

I = Iosin(2π/T(T/4) + π/2)

I = Iosin(π/2 + π/2)

I = Iosin(0)

I = 0

At t = T/2

I = Iosin(2π/T(T/2) + π/2)

I = Iosin(π + π/2)

I = Iosin(0)

I = Iosin(3π/2)

I = Iosin(540/2)

I = Iosin(270)

I = -Io

Note : Io = Imax

Both conditions are met, Hence, the unknown element is a CAPACITOR.

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Juan and Kuri are on a carousel. Juan is closer to the center of the carousel than Kuri. Which statement describes their tangent

Licemer1 [7]

Answer:

Juan and Kuri complete one revolution in the same time, but Juan travels a shorter distance and has a lower speed.

Explanation:

Since Juan is closer to the center and Kuri is away from the center so we can say that Juan will move smaller distance in one complete revolution

As we know that the distance moved in one revolution is given as

$d = 2\pi r$

also the time period of revolution for both will remain same as they move with the time period of carousel

Now we can say that the speed is given as

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

so Juan will have less tangential speed. so correct answer will be

Juan and Kuri complete one revolution in the same time, but Juan travels a shorter distance and has a lower speed.

6 0

3 years ago

Read 2 more answers

Can someone please help me with science.

alekssr [168]

Answer:

The answers to your questions are given below

Explanation:

22. The energy of an electromagnetic wave and it's frequency are related by the following equation:

E = hf

Where:

E => is the energy

h => is the Planck's constant

f => is the frequency

From the equation i.e E = hf, we can conclude that the energy of a wave is directly proportional to it's frequency. This implies that an increase in the frequency of the wave will lead to an increase in the energy of the wave and also, a decrease in the frequency will lead to a decrease in the energy of the wave.

23. Gamma ray and radio wave are both electromagnetic waves. All electromagnetic waves has a constant speed of 3×10⁸ m/s in space.

Thus, gamma ray and radio wave have the same speed in space.

3 0

2 years ago

19) A child on a sled starts from rest at the top of a 15.0° slope. If the trip to the bottom takes 15.2 s,

sveticcg [70]

Answer: 288.8 m

Explanation:

We have the following data:

$t=15.2 s$ is the time it takes to the child to reach the bottom of the slope

$V_{o}=0$ is the initial velocity (the child started from rest)

$\theta=15\°$ is the angle of the slope

$d$ is the length of the slope

Now, the Force exerted on the sled along the ramp is:

$F=ma$ (1)

Where $m$ is the mass of the sled and $a$ its acceleration

In addition, if we draw a free body diagram of this sled, the force along the ramp will be:

$F=mg sin \theta$ (2)

Where $g=9.8 m/s^{2}$ is the acceleration due gravity

Then:

$ma=mg sin \theta$ (3)

Finding $a$ :

$a=g sin \theta$ (4)

$a=9.8 m/s^{2} sin(15\°)$ (5)

$a=2.5 m/s^{2}$ (6)

Now, we will use the following kinematic equations to find $d$ :

$V=V_{o}+at$ (7)

$V^{2}=V_{o}^{2}+2ad$ (8)

Where $V$ is the final velocity

Finding $V$ from (7):

$V=at=(2.5 m/s^{2})(15.2 s)$ (9)

$V=38 m/s$ (10)

Substituting (10) in (8):

$(38 m/s)^{2}=2(2.5 m/s^{2})d$ (11)

Finding $d$ :

$d=288.8 m$

6 0

2 years ago

n 38 g rifle bullet traveling at 410 m/s buries itself in a 4.2 kg pendulum hanging on a 2.8 m long string, which makes the pend

Kitty [74]

Answer:

68cm

Explanation:

You can solve this problem by using the momentum conservation and energy conservation. By using the conservation of the momentum you get

$p_f=p_i\\mv_1+Mv_2=(m+M)v$

m: mass of the bullet

M: mass of the pendulum

v1: velocity of the bullet = 410m/s

v2: velocity of the pendulum =0m/s

v: velocity of both bullet ad pendulum joint

By replacing you can find v:

$(0.038kg)(410m/s)+0=(0.038kg+4.2kg)v\\\\v=3.67\frac{m}{s}$

this value of v is used as the velocity of the total kinetic energy of the block of pendulum and bullet. This energy equals the potential energy for the maximum height reached by the block:

$E_{fp}=E_{ki}\\\\(m+M)gh=\frac{1}{2}mv^2$

g: 9.8/s^2

h: height

By doing h the subject of the equation and replacing you obtain:

$(0.038kg+4.2kg)(9.8m/s^2)h=\frac{1}{2}(0.038kg+4.2kg)(3.67m/s)^2\\\\h=0.68m$

hence, the heigth is 68cm

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2 years ago

Martin needs to push a box up a ramp.

creativ13 [48]

Uh I think it is inertia but I could be wrong

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2 years ago