Yellow-green light has a wavelength of 560 nm. What is its frequency?

Argon gas enters steadily an adiabatic turbine at 900 kPa and 450C with a velocity of 80 m/s and leaves at 150 kPa with a veloc

Crazy boy [7]

Answer:

Temperature at the exit = $267.3 C$

Explanation:

For the steady energy flow through a control volume, the power output is given as

$W_{out}= -m_{f}(h_{2}-h_{1} + \frac{v_{2}^{2}}{2} - \frac{v_{1}^{2}}{2})$

Inlet area of the turbine = $60cm^{2}= 0.006m^{2}$

To find the mass flow rate, we can apply the ideal gas laws to estimate the specific volume, from there we can get the mass flow rate.

Assuming Argon behaves as an Ideal gas, we have the specific volume $v_{1}$

as

$v_{1}=\frac{RT_{1}}{P_{1}}=\frac{0.2081\times723}{900}=0.1672m^{3}/kg$

$m_{f}=\frac{1}{v_{1}}\times A_{1}V_{1} = \frac{1}{0.1672}\times(0.006)(80)=2.871kg/sec$

for Ideal gasses, the enthalpy change can be calculated using the formula

$h_{2}-h_{1}=C_{p}(T_{2}-T_{1})$

hence we have

$W_{out}= -m_{f}((C_{p}(T_{2}-T_{1}) + \frac{v_{2}^{2}}{2} - \frac{v_{1}^{2}}{2})$

$250= -2.871((0.5203(T_{2}-450) + \frac{150^{2}}{2\times 1000} - \frac{80^{2}}{2\times 1000})$

Note: to convert the Kinetic energy term to kilojoules, it was multiplied by 1000

evaluating the above equation, we have $T_{2}=267.3C$

Hence, the temperature at the exit = $267.3 C$

5 0

3 years ago

A spinning coil of wire is what moves the cone in a speaker, producing the sound. True/False

Georgia [21]

False, the spinning coil of wire that moves the cone in a speaker does not produces sound.

Explanation:

The wire coil is an electromagnet that is fixed to speaker cone. A normal magnet attached to the back of the speaker cone.When audio is sent in the form of short bursts of electric current to the speaker cone through the wire.

A magnetic field is induced when electric current allowed to pass through the coil. This magnetic field is repelled by the other magnet. This repulsion cause the cone to move forward. In the absence of electric current in the coil, the cone moves backward.

Thus sound waves are produced due to the resulting rarefaction and compression. So it is not the spinning coil of wire but he permanent magnet that produces the sound.

5 0

3 years ago

Read 2 more answers

What do the atoms of elements in the same group have in common? A. They have the same atomic numbers. B. They have the same aver

sergiy2304 [10]

Answer:

A. They have the same atomic numbers.

Explanation:

Elements are defined based on the atomic number, which is the number of protons in the nucleus: this means that atoms of the same element have always the same number of protons in their nuclei (and so, always the same atomic number).

The other choices are wrong because:

B. They have the same average atomic masses. --> this is false for isotopes, which are atoms of the same element having a different number of neutrons. Since the atomic mass is calculated from the sum of the masses of protons and neutrons in the nucleus, two isotopes of the same element have different atomic mass

C. They have the same number of electron shells. --> this can be false when an atom of an element loses/gains an electron, becoming an ion: in that case, the number of electron shells can change, since the number of electrons has changed.

D. They have the same number of electrons in their outermost shells. --> this is also false in case one of the atoms is an ion, since the number of electrons is different.

8 0

3 years ago

Which pair of variables defines motion?

masha68 [24]

Answer: position (x) and time (t)

Explanation:

A body is said to be in motion when its position changes with time with respect to a stationary observer.

Following are the types of motion:

Uniform motion: When equal amount of distance is covered in equal intervals of time.

Non-Uniform motion: When unequal amount of distance is covered in equal intervals of time.

Motion can be of the following types as well:

Rectilinear motion: when object moves in a straight line.

Circular motion: when object moves in a curved path.

Periodic motion: when motion repeats itself in fixed intervals of time.

Thus, in order to define motion, only two variables are required: position and time. Measuring these variables can determine whether the object is in motion or not and the type of motion.

5 0

2 years ago

Read 2 more answers

Choose all the answers that apply. The continents _____. were once connected have always been in the same location are slowly dr

svetoff [14.1K]

Answer: the correct options are

- were once connected

- are slowly drifting

Explanation: The continent is the main land mass of the earth which includes the following:

- Asia, Africa, Europe, Australia, North America, South America, and Antarctica.

These continents were once connected forming a supercontinent called PANGAEA

during the late palaeozoic and early mesozoic eras, millions of years ago.

Alfred Wegener, who is a German meteorologist, in 1912 came up with a hypothesis that the continents are slowly drifting the earth. He called the movement continental drift.

The continents rest on massive slabs of rock called tectonic plates. The plates are always moving and interacting in a process called plate tectonics. In recent studies, through the science of plate tectonics, we where able to understand the mechanism through which continental drift occurs. The mechanism includes:

- processes of seafloor spreading,

- rift valley formation, and

- subduction (where heavier tectonic plates sink beneath lighter ones).

7 0

3 years ago