Answer:
(a). The velocity of star is 
and the direction of star toward the earth.
(b). The shift is 0.0168 nm.
Explanation:
Given that,
Wavelength of spectral line = 663 nm
Wavelength of spectral line in lab = 645 nm
(a). We need to calculate the velocity
Using doppler's effect
Where, 
= change in wavelength
v = velocity
c = speed of light
Put the value into the formula
The direction of star toward the earth.
(b). Speed = 7800 m/s
We need to calculate the shift
Using formula of shift
Put the value into the formula
This shift is small compare to the the movement of Earth around the sun.
Hence, (a). The velocity of star is and the direction of star toward the earth.
(b). The shift is 0.0168 nm.
Mg = 6.2 x 9.81 = 60.822
This is also normal force.
Coefficient of friction times normal force is the force due to friction:
60.822 x 0.24 = 14.6N
F = MA so F(your force) - F(friction) = 6.2 x 0.5
= 3.1
Your answer is 3.1+ 14.6
I hope this is correct though I might be wrong.
-- 'Ca' (Calcium) is an element.
-- The proton has a positive charge.
-- Nuclear fusion results in the synthesis of atoms of new elements.
-- H₂O (water) is a chemical compound.
-- Nuclear fission is a decay of the nucleus.
-- The atomic number of an element is the number of protons
in each atom of it.
-- I suppose you're using the Greek letter <span>η ('eta', not 'nu')
to represent the neutron.
-- I suppose you're using ' e ' to represent the electron.
</span>
<span> If electricity and magnetism can create motion, can the reverse be true? Can motion and magnetism create electricity?</span>
When a car approaches you, the sound waves that reach you have a shorter wavelength and a higher frequency. You hear a sound with a higher pitch. When the car moves away from you, the sound waves that reach you have a longer wavelength and lower frequency.
?? ⬇️
An approaching source moves closer during period of the sound wave so the effective wavelength is shortened, giving a higher pitch since the velocity of the wave is unchanged. Similarly the pitch of a receding sound source will be lowered.
The Doppler effect is an effect observed in light and sound waves as they move toward or away from an observer. One simple example of the Doppler effect is the sound of an automobile horn. Picture a person standing on a street corner. A car approaches, blowing its horn.
Comparing two waves of the same wavelength, a higher frequency is associated with faster movement. Comparing two waves of different wavelengths, a higher frequency doesn't always indicate faster movement, although it can. Waves of different wavelengths can have the same frequency.
The pitch of a sound is our ear's response to the frequency of sound. Whereas loudness depends on the energy of the wave. ... The pitch of a sound depends on the frequency while loudness of a sound depends on the amplitude of sound waves.
