All categories

4 years ago

According to the doppler effect What appears to happen when a light source moves closer to an observer

1 answer:

7 1

When the distance between the source and the observer is DEcreasing, the observer sees light that has a<em> shorter wavelength</em> than the light actually had when it left the source.

It doesn't matter how the distance between them is decreasing. The source could be moving toward the observer, the observer could be moving toward the source, or they could both be moving in a way that makes the separation between them decrease as time goes on. The result is the same.

(When this is used in Astronomy and Astrophysics, the big trick is: How does the observer know what the wavelength actually WAS when the light left the source ?)

You might be interested in

Compare and contrast electric conductors and electric insulators. Give an example of each.

ludmilkaskok [199]

An example of conductors of heat would be iron pans. a example of electric insulators would be copper, gold and silver. to contrast conductors and insulators, insulators let electricity pass through them while conductors restricts electricity. both conductors and insulators can work with lithium and sodium.

3 0

3 years ago

Using the vocabulary words we have learned so far in this unit, describe what happens when something warms up.

Sidana [21]

When heat is added to a substance, the molecules and atoms vibrate faster. As atoms vibrate faster, the space between atoms increase. The motion and spacing of the particles determines the state of matter of the substance. The end result of increased molecular motion is that the object expands and takes up more space.

4 0

3 years ago

Read 2 more answers

g initial angular velocity of 39.1 rad/s. It starts to slow down uniformly and comes to rest, making 76.8 revolutions during the

MrRa [10]

Answer:

Approximately $-1.58\; \rm rad \cdot s^{-2}$ .

Explanation:

This question suggests that the rotation of this object slows down "uniformly". Therefore, the angular acceleration of this object should be constant and smaller than zero.

This question does not provide any information about the time required for the rotation of this object to come to a stop. In linear motions with a constant acceleration, there's an SUVAT equation that does not involve time:

$v^2 - u^2 = 2\, a\, x$ ,

where

$v$ is the final velocity of the moving object,
$u$ is the initial velocity of the moving object,
$a$ is the (linear) acceleration of the moving object, and
$x$ is the (linear) displacement of the object while its velocity changed from $u$ to $v$ .

The angular analogue of that equation will be:

$(\omega(\text{final}))^2 - (\omega(\text{initial}))^2 = 2\, \alpha\, \theta$ , where

$\omega(\text{final})$ and $\omega(\text{initial})$ are the initial and final angular velocity of the rotating object,
$\alpha$ is the angular acceleration of the moving object, and
$\theta$ is the angular displacement of the object while its angular velocity changed from $\omega(\text{initial})$ to $\omega(\text{final})$ .

For this object:

$\omega(\text{final}) = 0\; \rm rad\cdot s^{-1}$ , whereas
$\omega(\text{initial}) = 39.1\; \rm rad\cdot s^{-1}$ .

The question is asking for an angular acceleration with the unit $\rm rad \cdot s^{-1}$ . However, the angular displacement from the question is described with the number of revolutions. Convert that to radians:

$\begin{aligned}\theta &= 76.8\; \rm \text{revolution} \\ &= 76.8\;\text{revolution} \times 2\pi\; \rm rad \cdot \text{revolution}^{-1} \\ &= 153.6\pi\; \rm rad\end{aligned}$ .

Rearrange the equation $(\omega(\text{final}))^2 - (\omega(\text{initial}))^2 = 2\, \alpha\, \theta$ and solve for $\alpha$ :

$\begin{aligned}\alpha &= \frac{(\omega(\text{final}))^2 - (\omega(\text{initial}))^2}{2\, \theta} \\ &= \frac{-\left(39.1\; \rm rad \cdot s^{-1}\right)^2}{2\times 153.6\pi\; \rm rad} \approx -1.58\; \rm rad \cdot s^{-1}\end{aligned}$ .

7 0

3 years ago

F(x) = 3x^2+5x-14<br> Find f(-9)

Llana [10]

Answer:

f(-9) = 184

Explanation:

f(x)=3x²+5x-14

f(-9)= 3(-9)² +5(-9)-14 Order of Operations : Exponents

= 3(81)+5(-9)-14

= 243+5(-9)-14

= 243-45-14

= 198-14

f(-9)= 184

Hope this helps :)

8 0

3 years ago

What are parasites? Give some example

Inga [223]

Answer:

parasites are creatures the gain benefit off of other animals usually harming them eg:ticks on dogs

4 0

3 years ago