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3 years ago

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A pelican hunts fish in the water. As the pelican flies above the water’s surface, why must it aim for the fish in a slightly di

fferent place than where the fish appears to be located?
A. Light reflects off the fish, except for light of the wavelength the fish absorbs, making the fish hard to see.
B. Water absorbs most of the light, so not much light reaches the pelican’s eyes.
C. Energy from the ocean waves is transferred to the light waves.
D. Light waves are refracted as they travel from air to water.

1 answer:

GarryVolchara [31]3 years ago

5 0

Answer

A

Explanation

The light the fish absorbs is sunlight, the light reflecting is UV

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LC CIRCUIT: A 20.00-F capacitor is fully charged by a 100.00-V battery, then disconnected from the battery and connected in seri

klio [65]

Answer:

(a) $w=13.363\ rad/sec$

(b) $Q_m=2000\ coul$

(c) $E_{max}=100,000\ J$

(d) $I=25,197.63\ A$

(e) $I_{max}=26,726.12\ A$

Explanation:

<u>LC Circuit</u>

The dynamics of an LC circuit is explained as the energy stored in the capacitor C in the form of an electrical field is transferred to the inductor L as a magnetic field. The energy stored in a capacitor is

$\displaystyle E_c=\frac{CV^2}{2}$

Where V is the potential between its plates where a charge Q is stored. The relation between them is

$\displaystyle C=\frac{Q}{V}$

The energy stored in an inductor of self-inductance L is

$\displaystyle E_c=\frac{LI^2}{2}$

Where I is the current flowing through the inductor. If we apply the principle of conservation of energy, the loss of electric energy in the capacitor will transform into magnetic energy in the inductor and vice-versa.

The angular frequency of oscillation of a LC circuit is

$\displaystyle w=\sqrt{\frac{1}{LC}}$

The question provides the following data

$V_m=100\ V,\ C=20\ F,\ L=0.28\ mH=0.00028\ H$

(a) The angular frequency is

$\displaystyle w=\sqrt{\frac{1}{(0.00028)(20)}}$

$w=13.363\ rad/sec$

(b) When the voltage is at maximum, the charge will also be maximum, its value can be computed solving for Q

$\displaystyle C=\frac{Q_m}{V_m}$

$Q_m=V_mC=100(20)=2000$

$Q_m=2000\ coul$

(c) At t=0, the voltage is at maximum, so the energy stored is

$\displaystyle E_{max}=\frac{CV_m^2}{2}$

$\displaystyle E_{max}=\frac{20\ 100^2}{2}=100,000$

$E_{max}=100,000\ J$

(d) If the charge reaches 1/3 of the initial value, it means 2/3 of the charge were transformed in magnetic energy. Let's call $E_t$ to the transferred electric energy to magnetic energy, and $E_1$ to the remaining electric energy in the capacitor. Knowing $Q_1=1/3Q_m$

$\displaystyle Q_1=\frac{2000}{3}=666.67\ coul$

$\displaystyle V_1=\frac{666.67}{20}=33.33\ V$

$\displaystyle E_1=\frac{(20)\ 33.33^2}{2}=11,111.11\ J$

The energy transfered is

$E_t=100,000-11,111.11=88,888.89\ J$

We can compute the current solving for I in:

$\displaystyle E_t=\frac{LI^2}{2}$

$\displaystyle I=\sqrt{\frac{2E_t}{L}}$

Calculating I

$\displaystyle I=\sqrt{\frac{2(88,888.89)}{0.00028}}$

$I=25,197.63\ A$

(e) To find $I_{max}$ , we'll assume all the electric energy is transformed to magnetic, so

$\displaystyle I_{max}=\sqrt{\frac{2E_{max}}{L}}$

$\displaystyle I_{max}=\sqrt{\frac{2(100,000)}{0.00028}}$

$I_{max}=26,726.12\ A$

3 0

3 years ago

If a girl is running along a straight road with a uniform velocity 1.5m/s find her acceleration.

Brrunno [24]

If she is moving in a straight line at a constant speed,
then her acceleration is zero.

7 0

3 years ago

A new concrete mix is being designed to provide adequate compressive strength for concrete blocks. The specification for a parti

irinina [24]

Complete question:

new concrete mix is being designed to provide adequate compressive strength for concrete blocks. The specification for a particular application calls for the blocks to have a mean compressive strength µ greater than 1350 kPa. A sample of 100 blocks is produced and tested. Their mean compressive strength is 1356 kPa and their standard deviation is 70 kP

a) Find the p value.

b) Do you believe it is plausible that the blocks do not meet the specification, or are you convinced that they do? Expain your reasoning.

Answer:

a) p-value= 0.1949

b) It is possible the blocks do not meet the specifications

Explanation:

Given:

n = 100

Sample mean, X' = 1356

Standard deviation, s.d = 70

a) To find p- value.

Null hypothesis:

H0: u ≤ 1350

Alternative hypothesis:

H1 : u > 1350

The test statistic wll be:

$z= \frac{X'-u_o}{s.d/ \sqrt{n}}$

$= \frac{1356-1350}{70/\sqrt{100}}$

=0.86

The p value will be:

= P(z>0.86)

= 1-P(z≤0.86)

Using the normal distribution table, we now have:

1 - 0.8051

= 0.1949

P value = 0.1949

b) Since our p-value is 0.1949, we do not reject the null hypothesis, because the p-value, 0.1949, is not small. This means that it is possible the blocks do not meet the specifications.

5 0

3 years ago

Homer agin leads the varsity team in home runs. In a recent game, homer hit a 96 mi/hr sinking curve ball head on, sending it of

USPshnik [31]

Answer;

= 90600 m/s...

Explanation;

velocity of ball = 96 mi/hr = 42.916 m/s...

velocity of bat = -56mi/hr = -25.034m/s.. ( note the negativity here..)

time = 0.75 millisec = 0.75 * 10^-3 sec

acceleration = (velball - velbat) / time

= (42.916 - (-25.034)) / (0.75 * 10^-3)

=90600 m/s

6 0

3 years ago

Read 2 more answers

the guage pressure in a car tire is 30.0 psi when the air temperature is 0 C as the day warms up and brighten sun shines What is

Viktor [21]

Answer:

$P_2 = 33.297\ psi$

Explanation:

give,

Gauge pressure of car, P₁ = 30 psi

temperature,T₁ = 0° C = 0 + 273 = 273 K

Assuming temperature at the noon = 30° C

T₂ = 30 + 273 = 303 K

Pressure at this temperature, P₂ = ?

Using ideal gas equation

$\dfrac{P_1V_1}{T_1}=\dfrac{P_2V_2}{T_2}$

taking volume as in compressible V₁ = V₂

$\dfrac{P_1}{T_1}=\dfrac{P_2}{T_2}$

$\dfrac{30}{273}=\dfrac{P_2}{303}$

$P_2 = 303\times \dfrac{30}{273}$

$P_2 = 33.297\ psi$

Hence, Pressure of the at 30°C is equal to 33.297 psi.

3 0

3 years ago