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pickupchik [31]
3 years ago
11

A train travels 59 kilometers in 3 hours, and then 74 kilometers in 5 hours. What is its average speed?

Physics
1 answer:
dybincka [34]3 years ago
3 0
Average speed = (total distance) / (total time)

Total distance = 59 km + 74 km = 133 km

Total time = 3 hrs + 5 hrs  =  8 hrs

Average speed  =  (133 km) / (8 hrs)  =  16.625 km/hr
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Calculate the wavelengths of the first five members of the Lyman series of spectral lines, providing the result in units Angstro
Oduvanchick [21]

Answer:

Explanation:

The formula for hydrogen atomic  spectrum is as follows

energy of photon due to transition from higher orbit n₂ to n₁

E=13.6 (\frac{1}{n_1^2 } - \frac{1}{n_2^2})eV

For layman series n₁ = 1 and n₂ = 2 , 3 , 4 ,   ...   etc

energy of first line

E_1=13.6 (\frac{1}{1^2 } - \frac{1}{2 ^2})

10.2 eV

wavelength of photon = 12375 / 10.2 = 1213.2 A

energy of 2 nd line

E_2=13.6 (\frac{1}{1^2 } - \frac{1}{3 ^2})

= 12.08 eV

wavelength of photon = 12375 / 12.08 = 1024.4 A

energy of third line

E_3=13.6 (\frac{1}{1^2 } - \frac{1}{4 ^2})

12.75 e V

wavelength of photon = 12375 / 12.75 = 970.6 A

energy of fourth line

E_4=13.6 (\frac{1}{1^2 } - \frac{1}{5 ^2})

= 13.056 eV

wavelength of photon = 12375 / 13.05 = 948.3 A

energy of fifth line

E_5=13.6 (\frac{1}{1^2 } - \frac{1}{6 ^2})

13.22 eV

wavelength of photon = 12375 / 13.22 = 936.1 A

7 0
3 years ago
When an electron falls from a higher to a lower energy level in an atom, the photon released has a wavelength of 121.6 nm. What
yarga [219]

Answer:

\Delta E=1.64*10^{-18}J

Explanation:

The energy difference between the energy levels involved in the transition of the electron is directly proportional to the frequency of the emitted photon:

\Delta E=h\nu(1)

Where h is the Planck constant. The photon's frequency is inversely proportional to its wavelegth:

\nu=\frac{c}{\lambda}(2)

Here c is the speed of light. Replacing (2) in (1):

\Delta E=\frac{hc}{\lambda}\\\Delta E=\frac{(6.63*10^{-34}J\cdot s)(3*10^8\frac{m}{s})}{121.6*10^{-9}m}\\\Delta E=1.64*10^{-18}J

6 0
3 years ago
A 10.0 cm object is 5.0 cm from a concave mirror that has a focal length of 12 cm. What is the distance between the image and th
fiasKO [112]
Let's use the mirror equation to solve the problem:
\frac{1}{f}= \frac{1}{d_o}+ \frac{1}{d_i}
where f is the focal length of the mirror, d_o the distance of the object from the mirror, and d_i the distance of the image from the mirror.
For a concave mirror, for the sign convention f is considered to be positive. So we can solve the equation for d_i by using the numbers given in the text of the problem:
\frac{1}{12 cm}= \frac{1}{5 cm}+ \frac{1}{d_i}
\frac{1}{d_i}= -\frac{7}{60 cm}
d_i = -8.6 cm
Where the negative sign means that the image is virtual, so it is located behind the mirror, at 8.6 cm from the center of the mirror.
6 0
3 years ago
Read 2 more answers
Select all the correct answers.
chubhunter [2.5K]

Answer:

Water breaking down into hydrogen and oxygen is a decomposition reaction

Hydrogen and oxygen combining to form water is a synthesis reaction

Explanation:

A decomposition reaction is a chemical reaction that involves the breakdown of a chemical reactant entity into two or more simpler product fragments

Water H₂O undergoes a decomposition reaction by breaking down into hydrogen, H₂,, and oxygen, O₂, as follows;

2H₂O (l) → 2H₂ (g) + O₂ (g)

A synthesis reaction is a reaction that involves the chemical combination of two or more dissimilar molecules or atoms to produce a different compound or molecule

Water, H₂O, is formed by a synthesis reaction of hydrogen, H₂,, and oxygen, O₂, combining as follows;

2H₂ + O₂  → 2H₂O

5 0
3 years ago
A 75.0 kg person is on a Ferris Wheel that has a radius R = 16 m. The tangential velocity of the Ferris Wheel is 8.25 m/s. Calcu
Dovator [93]

Answer:

The period of rotation is

T=8.025s

Explanation:

The person is undergoing simple harmonic motion on the wheel

Given data

mass of the person =75kg

Radius of wheel r=16m

Velocity =8.25m/s

The oscillating period of simple harmonic motion is given as

T=(2*pi)/2=2*pi √r/g

Assuming that g=9.81m/s

Substituting our data into the expression we have

T=2*3.142 √ 16/9.81

T=6.284*1.277

T=8.025s

3 0
3 years ago
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