If the peak wavelength of a star at rest is 615 nm, then what peak wavelength is observed when the star is traveling 2,500,000 m/s toward the Earth.

1612903nm

Explanation:

Doppler effect can be regarded as the change in frequency of a wave with respect toobserver that move relative to the wave source

We can expressed as

(λo - λs)/λs = v/s

λo= peak wavelength

λs= peak wavelength observed

C= speed of light

(λo -615×10^9 )/615×10^9 = 2,500,000/(3×10^8)

1.5375=3×10^8λo -184.5

1.5375+184.5=3×10^8λo

186=3×10^8λo

λo=1612903nm

Therefore the peak wavelength that is observed when the star is traveling away from the eart to the velocity given is 1612903nm

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.