In an INELASTIC collision between two objects:

Which of the following is a physical change?

Talja [164]

I believe c is correct......

5 0

4 years ago

Calculate the number of vacancies per cubic meter at 1000°C for a metal that has an energy for vacancy formation of 1.22 eV/atom

Daniel [21]

To solve this problem, it is necessary to take into account the concepts of the number of vacations N_v at a given temperature as well as the calculation of the number of atom sites per cubic meter.

For definition the number of atomic sites per cubic meter is given as,

$N = \frac{N_A\rho}{A}$

Where,

$N_A = 6.02210^{23}atoms/mol \rightarrow$ Avogadro's number

$\rho$ density

A = Atomic weight

Replacing with our values we have

$N = \frac{(6.02210^{23}atoms/mol)(6.25g/cm^3)(10^6cm^3/m^3)}{37.4g/mol}$

$N = 1*10^{29}atoms/m^3$

At the same time we know that the number of vacancies $N_v$ is defined as,

$[tex]N_v = Ne^{-\frac{Q_v}{KT}}$ [/tex]

Where,

$Q_v =$ Energy of vacancy

$K = 8.62*10^{-5} ev/Atom.K \rightarrow$ Boltzman constant

T = Temperature

Replacing with the values given we have

$N_v = (1*10^{29}atoms/m^3)e^{-\frac{1.22eV/atom}{(8.62*10^{-5}eV/atom.K)(1273K)}}$

$N_v = 1.49*10^{24}m^{-3}$

Therefore the number of vacancies per cubit meter at 1000°C is $N_v = 1.49*10^{24}m^{-3}$

5 0

4 years ago

1. how can the school and community help you to stay healthy and be aware of your health status?

Molodets [167]

Answer:

1.school and community helps in growth and development of you social health as when u learn how to be compatible with the people around you, you will do better in life

2. by trying and solving

by not giving

by innovating

by being motivated

BY KNOWING THAT U CAN DO IT

7 0

3 years ago

1) Why do the different rocks exposed in the Grand Canyon appear in layers for the most part? Where are the oldest layers of roc

fiasKO [112]

This is what i put:

<span> The Grand Canyon is made up of sedimentary rock; over time, sediments formed into layers. The layers on the bottom are the oldest, and the layers on the top are the youngest and newest.

Try and paraphrase though</span>

5 0

3 years ago

Light with a wavelength range of 141–295 nm shines on a silicon surface in a photoelectric effect apparatus, and a reversing pot

Ksju [112]

Answer:

a) the longest wavelength of the light that will eject electrons from the silicon surface is 258.7891 nm

b) maximum kinetic energy will electrons reach the anode is 0.5098 eV

Explanation:

Given:

Wavelength range = 141-295 nm

Potential of 3.5 V

For the silicon, the work function is Φ = 4.8 eV = 7.68x10⁻¹⁹J

Questions:

a) What is the longest wavelength of the light that will eject electrons from the silicon surface, λ = ?

b) With what maximum kinetic energy will electrons reach the anode,

a) The longest wavelength that will eject electrons:

$\lambda =\frac{hc}{\phi }$

Here

h = Planck's constant = 6.625x10⁻³⁴J s

c = speed of light = 3x10⁸m/s

Substituting values:

$\lambda =\frac{6.625x10^{-34}*3x10^{8} }{7.68x10^{-19} } =2.588x10^{-7} m=258.7891nm$

b) The maximum kinetic energy (one electron):

$K=\frac{hc}{\lambda } -\phi =\frac{6.625x10^{-34}*3x10^{8} }{141x10^{-9} } -7.68x10^{-19} =6.416x10^{-19} J=4.0098eV$

Now, you need to calculate the potential difference:

$K'=eV$

Here

e = charge of electron = 1.6x10⁻¹⁹C

Substituting:

$K'=1.6x10^{-19} *3.5=5.6x10^{-19} J=3.5eV$

Now, the maximum kinetic energy of the electrons:

Kmax = 4.0098 - 3.5 = 0.5098 eV

6 0

4 years ago