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3 years ago

In most cases, what happens to a liquid when it cools?

Physics

1 answer:

erik [133]3 years ago

7 0

Answer:

Option (A) and (F)

Explanation:

As the liquid cools down, it means the temperature decreases the density of the liquid increases in most o the cases.

Now the volume is inversely proportional to the density of substance so density increases.

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(a) Find the energy of the ground state (n = 1) and the first two excited states of an electron in a one-dimensional box of leng

const2013 [10]

(a) $3.77\cdot 10^5 MeV, 1.51\cdot 10^6 MeV, 3.39\cdot 10^3 GeV$

The energy levels of an electron in a box are given by

$E_n = \frac{n^2 h^2}{8mL^2}$

where

n is the energy level

$h=6.63\cdot 10^{-34}Js$ is the Planck constant

$m=9.11\cdot 10^{-31}kg$ is the mass of the electron

$L=1.0\cdot 10^{-15} m$ is the size of the box

Substituting n=1, we find the energy of the ground state:

$E_1 = \frac{1^2 (6.63\cdot 10^{-34}^2}{8(9.11\cdot 10^{-31}(1.0\cdot 10^{-15})^2}=6.03\cdot 10^{-8}J$

Converting into MeV,

$E_1 = \frac{6.03\cdot 10^{-8} J}{1.6\cdot 10^{-19} J/eV}\cdot 10^{-6} MeV/eV =3.77\cdot 10^5 MeV$

Substituting n=2, we find the energy of the first excited state:

$E_2 = \frac{2^2 (6.63\cdot 10^{-34}^2}{8(9.11\cdot 10^{-31}(1.0\cdot 10^{-15})^2}=2.41\cdot 10^{-7}J$

Converting into MeV,

$E_2 = \frac{2.41\cdot 10^{-7} J}{1.6\cdot 10^{-19} J/eV}\cdot 10^{-6} MeV/eV =1.51\cdot 10^6 MeV$

Substituting n=3, we find the energy of the second excited state:

$E_3 = \frac{3^2 (6.63\cdot 10^{-34}^2}{8(9.11\cdot 10^{-31}(1.0\cdot 10^{-15})^2}=5.43\cdot 10^{-7}J$

Converting into GeV,

$E_3 = \frac{5.43\cdot 10^{-7} J}{1.6\cdot 10^{-19} J/eV}\cdot 10^{-9} GeV/eV =3.39\cdot 10^3 GeV$

(b) $1.10 \cdot 10^{-18} m$

The energy of the emitted radiation is equal to the energy difference between the two levels, so:

$E=E_2 - E_1 = 2.41\cdot 10^{-7}J - 6.03\cdot 10^{-8} J=1.81\cdot 10^{-7} J$

And the energy of the electromagnetic radiation is

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

where c is the speed of light; so, re-arranging the formula, we find the wavelength:

$\lambda=\frac{hc}{E}=\frac{(6.63\cdot 10^{-34} Js)(3\cdot 10^8 m/s)}{1.81\cdot 10^{-7}J}=1.10 \cdot 10^{-18} m$

(c) $6.59 \cdot 10^{-19} m$

The energy of the emitted radiation is equal to the energy difference between the two levels, so:

$E=E_3 - E_2 = 5.43\cdot 10^{-7} J - 2.41\cdot 10^{-7}J =3.02\cdot 10^{-7} J$

Using the same formula as before, we find the corresponding wavelength:

$\lambda=\frac{hc}{E}=\frac{(6.63\cdot 10^{-34} Js)(3\cdot 10^8 m/s)}{3.02\cdot 10^{-7}J}=6.59 \cdot 10^{-19} m$

(d) $4.12 \cdot 10^{-19} m$

The energy of the emitted radiation is equal to the energy difference between the two levels, so:

$E=E_3 - E_1 = 5.43\cdot 10^{-7} J - 6.03\cdot 10^{-8}J =4.83\cdot 10^{-7} J$

Using the same formula as before, we find:

$\lambda=\frac{hc}{E}=\frac{(6.63\cdot 10^{-34} Js)(3\cdot 10^8 m/s)}{4.83\cdot 10^{-7}J}=4.12 \cdot 10^{-19} m$

7 0

3 years ago

Please write ONE complete sentence describing the relationship between Kinetic Energy and Gravitational Potential Energy in a sy

Scilla [17]

Answer:

Explanation:

The sum of kinetic and potential energy is the mechanical energy of the system. Assuming the energy of the system is conserved, which it is in your case, then the initial mechanical energy will equal the final mechanical energy. This relationship is very useful in mechanics.

3 0

2 years ago

Which type of energy is water held back by a dam?

stepladder [879]

Answer: hydroelectric dams

Explanation: Enormous energy is stored in water held back by hydroelectric dams. The energy is transformed into (a form of kinetic energy) as it falls across the dam. The falling water strikes the blades of a turbine and makes them spin, and the then turns the shaft of a generator.

8 0

3 years ago

Read 2 more answers

Which of the following is an example of frontier research?

riadik2000 [5.3K]

Testing the electrical resistance of different materials. it is the answer

3 0

3 years ago

If a toy has a mass of 1 kg, it has an Earth weight of

marshall27 [118]

Answer:

The answer is 9.8 N

Explanation:

As we know that the weight of an object is the amount of gravitational force acting on the object in an upward direction if the weight is acting is the downward direction.

The formula of weight:

W = Mass x Gravitational force

W = m x g

Given data:

Mass =1 kg

g = 9.8 ms-2

W = 1kg x 9.8 ms-2 = 9.8 kgms-2 ( 1 kgms-2 = N)

SO,

W = 9.8 N

The toy has an earth weight of 9.8 N.

4 0

3 years ago