PHYSICS HIGH SCHOOL

Slick Willy is in traffic court (again) contesting a $50.00 ticket for running a red light. "You see, your Honor, as I was approaching the light, it appeared yellow to me because of the Doppler effect. The red light from the traffic signal was shifted up in frequency because I was traveling towards it, just like the pitch of an approaching car rises as it approaches you." a. Calculate how fast Slick Willy must have been driving, in meters per second, to observe the red light (wavelength of 687 nm) as yellow (wavelength of 570 nm). (Treat the traffic light as stationary, and assume the Doppler shift formula for sound works for light as well.)

Answers

Answer 1

Answer:

Answer:

$6.11*10^7m/s$

Explanation:

The Doppler effect formula for an observer approaching a source is given by equation (1);

$f_o=(f(v+v_o))/(v-v_s)...................(1)$

where $f_o$ is the frequency perceived by the observer, v is the actual velocity of the wave in air, $v_o$ is the velocity of the observer, $v_s$ is the velocity of the source and $f$ is the actual frequency of the wave.

The actual velocity v of light in air is $3*10^8m/s$ . The relationship between velocity, frequency and wavelength $\lambda$ is given by equation (2);

$v=\lambda f...........(2)$

therefore;

$f=(v)/(\lambda)...............(3)$

We therefore use equation (3) to find the actual frequency of light emitted and the frequency perceived by Slick Willy.

Actual wavelength $\lambda$ of light emitted is 678nm, hence actual frequency is

given by;

$f=(3*10^8)/(687*10^(-9))\nf=4.37*10^(14)Hz$

Also, the frequency perceived by Slick Willy is given thus;

$f_o=(3*10^8)/(570*10^(-9))\nf=5,26*10^(14)Hz$

The velocity $v_s$ of the source light is zero since the traffic light was stationary. Substituting all parameters into equation (1), we obtain the following;

$5.26*10^(14)=(4.37*10^(14)(3*10^(8)+v_o))/(3*10^8-0)$

We then simplify further to get $v_o$

$10^(14)$ cancels out from both sides, so we obtain the following;

$5.26*3*10^8=4.37(3*10^8+v_o)$

$15.78*10^8=13.11*10^8+4.37v_o\n4.37v_o=15.78*10^8-13.11*10^8\n4.37v_o=2.67*10^8$

Hence;

$v_o=(2.67*10^8)/(4.37)\nv_o=6.11*10^7m/s$

Answer 2

Answer:

Answer:

61578948 m/s

Explanation:

λ $_(actual)$ = λ $_(observed)$ $(c+v_(o))/(c)$

687 = 570 $((3 * 10^(8) +v_(o) )/(3 * 10^(8)) )$

$v_(o)$ = 61578948 m/s

So Slick Willy was travelling at a speed of 61578948 m/s to observe this.

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When magnesium (Mg2+) and fluorine (F1-) combine in an ionic bond, the resulting formula will be A) Mg2F.

B) Mg2F2.

C) MgF.

D) MgF2.

Answers

Answer is: D) MgF₂.

Magnesium fluoride is salt, ionic compound.

1) Magnesium (Mg) is metal from 2. group of Periodic table of elements and has low ionisation energy and electronegativity, which means it easily lose valence electons (two valence electrons).

Magnesium has atomic number 12, which means it has 12 protons and 12 electrons. It lost two electrons to form magnesium cation (Mg²⁺) with stable electron configuration like closest noble gas neon (Ne) with 10 electrons.

Electron configuration of magnesium ion: ₁₂Mg²⁺ 1s² 2s² 2p⁶.

2) Fluorine (F) is nonmetal with greatest electronegativity, which meand it easily gain electrons.

Fluorine jas atomic number 9, which means it has 9 protons and 9 electrons. It gain one electron to form fluorine anion (F⁻) with stable electron configuration like closest noble gas neon (Ne) with 10 electrons.

Electron configuration of fluorine ion: ₉F⁻ 1s² 2s² 2p⁶.

The fluorine has one spare electron per atom and the magnesium has a need for 2. This means for one magnesium you need two fluorine atoms making the formula MgF2.

Two point charges are brought closer together, increasing the force between them by a factor of 25. By what factor was their separation decreased? In other words, if r1 is the original separation and r2 is the final separation, what is the ratio r1/r2?

Answers

Answer: 1/5

Explanation: The force between the two charge is inversely proportional to the square distance between charges so as the force increased a factor of 25 the distance can reduced divided by a factor of 5.

While watching a recent science fiction movie, one Klingon spaceship blows up a Droid spaceship with a laser gun. The Klingon crew watches out the port window and covers their ears to muffle the noise from the explosion. Scientifically, this scene is inaccurate becauseA) light can not reflect off objects in the vacuum of space.
B) they would not be able to see anything outside the window.
C) lasers can not be transmitted through the vacuum of space.
D) the sound of the explosion would not be transmitted back to their ship.

Answers

Scientifically this scene is inaccurate because the sound of the explosion would not be transmitted back to their ship. The correct option among all the options that are given in the question is the last option or option "D". As sound cannot travel through a vacuum, so it is not possible for the crew to hear the sound of explosion.

Answer:

D. the sound of the explosion would not be transmitted back to their ship.

Explanation:

Sound is a type of mechanical wave so it needs a solid to move through. Since space is a vacuum, the Klingon crew would not be able to hear the explosion.

The photo shows a simple electric circuit.Which part of an electric circuit resists the flow of charge when it changes electrical energy into other forms of energy?

A.
part B - copper wires

B.
part A - battery

C.
part C - switch

D.
part D - lightbulb

Answers

The part of an electric circuit that resist the flow of charge when it changes electrical energy into other forms of energy would be : D. Lightbulb
It convert electrical energy into heat and light energy, which resist the flow of charge during the process

hope this helps

Answer: I know this is from 2016 but I am going to confirm that it is in fact D - Light bulb

Explanation: I took the test in K-12.

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d. colloids

Answers

The pure substances are c. homogenous mixtures

I think it's C hope this help

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Answers

Well, first of all, the truck's velocity is constantly changing, not 'uniform'.
Velocity consists of speed and direction. So, even if the truck's speed is
constant, its direction keeps changing as long as it's on a circular curve,
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The force needed to keep a mass moving in a circle is

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   3300 N = (1600 kg) (13 m/s)² / R

   3300 kg-m/s² = (1600 kg) (169 m²/s²) / R

   R = (1600 kg) · (169 m²/s²) / (3300 kg·m/s²)

   = (1600 · 169 / 3300) meters

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The Correct answer to this question for Penn Foster Students is: 81.94m

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