The book that weighs less
Your diagram should include four forces:
• the box's weight, pointing down (magnitude <em>w</em> = 43.2 N)
• the normal force, pointing up (mag. <em>n</em>)
• the applied force, pointing the direction in which the box is sliding (mag. <em>p</em> = 6.30 N, with <em>p</em> for "pull")
• the frictional force, pointing oppoiste the applied force (mag. <em>f</em> )
The box is moving at a constant speed, so it is inequilibrium and the net forces in both the vertical and horizontal directions sum to 0. By Newton's second law, we have
<em>n</em> + (-<em>w</em>) = 0
and
<em>p</em> + (-<em>f</em> ) = 0
So then the forces have magnitudes
<em>w</em> = 43.2 N
<em>n</em> = <em>w</em> = 43.2 N
<em>p</em> = 6.30 N
<em>f</em> = <em>p</em> = 6.30 N
Answer:
The Balmer series refers to the spectral lines of hydrogen, associated to the emission of photons when an electron in the hydrogen atom jumps from a level to the level .
The wavelength associated to each spectral line of the Balmer series is given by:
where is the Rydberg constant for hydrogen, and where is the initial level of the electron that jumps to the level n = 2.
The first few spectral lines associated to this series are withing the visible part of the electromagnetic spectrum, and their wavelengths are:
656 nm (red, corresponding to the transition )
486 nm (green, )
434 nm (blue, )
410 nm (violet, )
All the following lines lie in the ultraviolet part of the spectrum. The limit of the Balmer series, corresponding to the transition , is at 364.6 nm.