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3 years ago

They don't have an Astronomy Section and I believe that this falls the closest to Physics

1 answer:

5 0

The only thing we know of so far that can shift light to longer wavelengths is the "Doppler" effect. If the source and the observer are moving apart, then the observer sees wavelengths that are longer than they should be. If the source and the observer are moving toward each other, then the observer sees wavelengths that are shorter than they should be. It works for ANY wave ... sound, light, water etc. The trick is to know what the wavelength SHOULD be. If you know that, then you can tell whether you and the source are moving together or apart, and you can even tell how fast. If the lines in a star"s spectrum are at wavelengths that are too long, then from everything we know right now, the star and Earth are moving apart.

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Suppose that a wind is blowing in the direction S45°E at a speed of 30 km/h. A pilot is steering a plane in the direction N60°E

Kay [80]

Answer:

The true course: $40.29^\circ$ north of east

The ground speed of the plane: 96.68 m/s

Explanation:

Given:

$V_w$ = velocity of wind = $30\ km/h\ S45^\circ E = (30\cos 45^\circ\ \hat{i}-30\sin 45^\circ\ \hat{j})\ km/h = (21.21\ \hat{i}-21.21\ \hat{j})\ km/h$

$V_p$ = velocity of plane in still air = $100\ km/h\ N60^\circ E = (100\cos 60^\circ\ \hat{i}+100\sin 60^\circ\ \hat{j})\ km/h = (50\ \hat{i}+86.60\ \hat{j})\ km/h$

Assume:

$V_r$ = resultant velocity of the plane

$\theta$ = direction of the plane with the east

Since the resultant is the vector addition of all the vectors. So, the resultant velocity of the plane will be the vector sum of the wind velocity and the plane velocity in still air.

$\therefore V_r = V_p+V_w\\\Rightarrow V_r = (50\ \hat{i}+86.60\ \hat{j})\ km/h+(21.21\ \hat{i}-21.21\ \hat{j})\ km/h\\\Rightarrow V_r = (71.21\ \hat{i}+65.39\ \hat{j})\ km/h$

Let us find the direction of this resultant velocity with respect to east direction:

$\theta = \tan^{-1}(\dfrac{65.39}{71.21})\\\Rightarrow \theta = 40.29^\circ$

This means the the true course of the plane is in the direction of $40.29^\circ$ north of east.

The ground speed will be the magnitude of the resultant velocity of the plane.

$\therefore Magnitude = \sqrt{71.21^2+65.39^2} = 96.68\ km/h$

Hence, the ground speed of the plane is 96.68 km/h.

5 0

3 years ago

A bowling ball with a negative initial velocity slows down as it rolls down the lane toward the pins. Is the bowling ballâs acce

stiv31 [10]

Answer:

positive

Explanation:

The ball is rolling down with a negative velocity, but the velocity is slowing down. therefore the velocity must increase in order for the ball to slow down.

For example let the ball's initial velocity be -15 m/s. and it is slowing down to let's say -13 m/s. Well this means that it's velocity has increase by 2 m/s. So, its acceleration is positive.

5 0

3 years ago

A rigid, nonconducting tank with a volume of 4 m3 is divided into two unequal parts by a thin membrane. One side of the membrane

kondor19780726 [428]

The final temperature of the system will be equal to the initial temperature, and which is 373K. The work done by the system is 409.8R Joules.

To find the answer, we need to know about the thermodynamic processes.

<h3>How to find the final temperature of the gas?</h3>

Any processes which produce change in the thermodynamic coordinates of a system is called thermodynamic processes.
In the question, it is given that, the tank is rigid and non-conducting, thus, dQ=0.
The membrane is raptured without applying any external force, thus, dW=0.
We have the first law of thermodynamic expression as,

$dU=dQ-dW$

Here it is zero.

$dU=0$ ,

As we know that,

$dU=C_pdT=0\\\\thus, dT=0\\\\or , T=constant\\\\i.e, T_1=T_2$

Thus, the final temperature of the system will be equal to the initial temperature,

$T_1=T_2=100^0C=373K$

We found that the process is isothermal,
Thus, the work done will be,

$W=RT*ln(\frac{V_2}{V_1} )=373R*ln(\frac{4}{\frac{4}{3} })\\ \\W=409.8R J$

Where, R is the universal gas constant.

<h3>What is a reversible process?</h3>

Any process which can be made to proceed in the reverse direction is called reversible process.
During which, the system passes through exactly the same states as in the direct process.

Thus, we can conclude that, the final temperature of the system will be equal to the initial temperature, and which is 373K. The work done by the system is 409.8R Joules.

Learn more about thermodynamic processes here:

brainly.com/question/28067625

#SPJ1

7 0

1 year ago

Read 2 more answers

This whole worksheet. I am not good at this and I am completely lost

Ket [755]

1.) potential energy
2.)potential and kinetic
3.)The roller coaster car has the most kinetic energy at point X i know this because the car is moving and kinetic energy has the power to move or change things therefore point X is when the roller coaster car has the most energy.
4.)potential energy
5.)kinetic energy
6.) potential and kinetic energy

3 0

3 years ago

_________ is a layer of the earth that is classified not by composition

Sidana [21]

Answer:

Asthenosphere

Explanation:

The asthenosphere is a part of the upper mantle just below the lithosphere that is involved in plate tectonic movement and isostatic adjustments.

7 0

3 years ago