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Sunny_sXe [5.5K]
2 years ago
7

Is work being done on a barbell when a weight lifter is holding the barbell over his head?

Physics
1 answer:
AVprozaik [17]2 years ago
7 0
I don’t see any picture sorry I wish I can help tho
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A spring balance attempts to drag an object across a table, but the object does not move because of the force of friction acting
Luda [366]
Moving
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4 0
2 years ago
Use the Bohr model to address this question. When a hydrogen atom makes a transition from the 5 th energy level to the 2nd, coun
iris [78.8K]

Answer:

A. 2.82 eV

B. 439nm

C. 59.5 angstroms

Explanation:

A. To calculate the energy of the photon emitted you use the following formula:

E_{n1,n2}=-13.4(\frac{1}{n_2^2}-\frac{1}{n_1^2})     (1)

n1: final state = 5

n2: initial state = 2

Where the energy is electron volts. You replace the values of n1 and n2 in the equation (1):

E_{5,2}=-13.6(\frac{1}{5^2}-\frac{1}{2^2})=2.82eV

B. The energy of the emitted photon is given by the following formula:

E=h\frac{c}{\lambda}   (2)

h: Planck's constant = 6.62*10^{-34} kgm^2/s

c: speed of light = 3*10^8 m/s

λ: wavelength of the photon

You first convert the energy from eV to J:

2.82eV*\frac{1J}{6.242*10^{18}eV}=4.517*10^{-19}J

Next, you use the equation (2) and solve for λ:

\lambda=\frac{hc}{E}=\frac{(6.62*10^{-34} kg m^2/s)(3*10^8m/s)}{4.517*10^{-19}J}=4.39*10^{-7}m=439*10^{-9}m=439nm

C. The radius of the orbit is given by:

r_n=n^2a_o   (3)

where ao is the Bohr's radius = 2.380 Angstroms

You use the equation (3) with n=5:

r_5=5^2(2.380)=59.5

hence, the radius of the atom in its 5-th state is 59.5 anstrongs

8 0
3 years ago
In a double-slit experiment, light from two monochromatic light sources passes through the same double slit. The light from the
Dmitrij [34]

Answer:

\lambda_2 = 573.3 nm

Explanation:

As we know that the position of maximum intensity on the screen is given as

y = \frac{N\lambda L}{d}

here we know that

\lambda = wavelength

L = distance of the screen

d = distance between two slits

now we know that the position of 8th maximum intensity is same as that of 9th maximum on the screen

so we have

\frac{N_1\lambda_1 L}{d} = \frac{N_2 \lambda_2 L}{d}

so here we have

8 (645 nm) = 9 \lambda_2

\lambda_2 = 573.3 nm

4 0
3 years ago
When a guitar string plays the note "a," the string vibrates at 440 hz ?
Rama09 [41]
Yes, that's correct. The note "A" (which is used to tune the other strings of the guitar) corresponds to a frequency of 440 Hz.
8 0
2 years ago
What simple machines are used to create the shovel?
erastovalidia [21]

Answer:

I believe a wedge and a lever

Explanation:

7 0
3 years ago
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