Increasing cardiorespiratory fitness levels is difficult for experienced athletes because _________

Be sure to answer all parts. Consider the following energy levels of a hypothetical atom: E4 −2.01 × 10−19 J E3 −5.71 × 10−19 J

pashok25 [27]

(a) 159 nm

First of all, let's calculate the energy difference between the level E1 and E4:

$\Delta E=E_4 -E_1 = -2.01\cdot 10^{-19}J-(-1.45\cdot 10^{-18} J)=1.25\cdot 10^{-18} J$

Now we know that this energy difference is related to the wavelength of the absorbed photon by

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

where

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

$c=3\cdot 10^8 m/s$ is the speed of light

$\lambda$ is the wavelength of the photon

Solving for $\lambda$ , we find

$\lambda=\frac{hc}{\Delta E}=\frac{(6.63\cdot 10^{-34} Js)(3\cdot 10^8 m/s)}{1.25\cdot 10^{-18} J}=1.59\cdot 10^{-7} m = 159 nm$

b) 293 nm

As done in part a), let's calculate the energy difference between the level E2 and E3:

$\Delta E=E_3 -E_2 = -5.71\cdot 10^{-19}J-(-1.25\cdot 10^{-18} J)=6.79\cdot 10^{-19} J$

this energy difference is related to the wavelength of the absorbed photon by

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

Solving for $\lambda$ again, we find

$\lambda=\frac{hc}{\Delta E}=\frac{(6.63\cdot 10^{-34} Js)(3\cdot 10^8 m/s)}{6.79\cdot 10^{-18} J}=2.93\cdot 10^{-7} m = 293 nm$

c) 226 nm

As done in part a) and b), let's calculate the energy difference between the level E1 and E3:

$\Delta E=E_3 -E_1 = -5.71\cdot 10^{-19}J-(-1.45\cdot 10^{-18} J)=8.79\cdot 10^{-19} J$

this energy difference is related to the wavelength of the emitted photon by

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

Solving for $\lambda$ again, we find

$\lambda=\frac{hc}{\Delta E}=\frac{(6.63\cdot 10^{-34} Js)(3\cdot 10^8 m/s)}{8.79\cdot 10^{-18} J}=2.26\cdot 10^{-7} m = 226 nm$

4 0

3 years ago

What layer of the atmosphere is made mostly of hydrogen and helium?

ikadub [295]

On Earth, none of the atmosphere is.

6 0

3 years ago

Which of the following compounds is not likely to have ionic bonds? Question 5 options: LiF NaCl CH4 MgF2

Harrizon [31]

Answer:

CH4

Explanation:

CH4 is joined together by a covalent bond, aka a bond between two non-metals. Non-metals are found on the right side of the periodic table and include Carbon (C) and Hydrogen. Although Hydrogen is technically on the left side of the table, it has the characteristics of a non-metal. Futhermore, Ionic bonds generally are between an element on the right joined with an element on the left. This is because ionic bonds want charges that will cancel out to create a neutral molecule.

example: LiF

Li→ Li+

F→F-

(Li+)+(F-)=charges cancel out.

7 0

3 years ago

An electron moves in a region where the magnetic field is uniform and has a magnitude of 80 μT. The electron follows a helical p

sladkih [1.3K]

Answer:

3.4 x 10⁴ m/s

Explanation:

Consider the circular motion of the electron

B = magnetic field = 80 x 10⁻⁶ T

m = mass of electron = 9.1 x 10⁻³¹ kg

v = radial speed

r = radius of circular path = 2 mm = 0.002 m

q = magnitude of charge on electron = 1.6 x 10⁻¹⁹ C

For the circular motion of electron

qBr = mv

(1.6 x 10⁻¹⁹) (80 x 10⁻⁶) (0.002) = (9.1 x 10⁻³¹) v

v = 2.8 x 10⁴ m/s

Consider the linear motion of the electron :

v' = linear speed

x = horizontal distance traveled = 9 mm = 0.009 m

t = time taken = $\frac{2\pi m}{qB}$ = $\frac{2\pi (9.1\times 10^{-31})}{(1.6\times 10^{^{-19}})(80\times 10^{-6})}$ = 4.5 x 10⁻⁷ sec

using the equation

x = v' t

0.009 = v' (4.5 x 10⁻⁷)

v' = 20000 m/s

v' = 2 x 10⁴ m/s

Speed is given as

V = sqrt(v² + v'²)

V = sqrt((2.8 x 10⁴)² + (2 x 10⁴)²)

v = 3.4 x 10⁴ m/s

6 0

4 years ago

Which element has an isotope with 43 neutrons and a mass number of 76?

nexus9112 [7]

Answer:

B. Arsenic

Explanation:

76 - 43 = 33 protons

on a periodic table element 33 is Arsenic

7 0

3 years ago

Increasing cardiorespiratory fitness levels is difficult for experienced athletes because __________.