2. Consider a situation where a source is emitting a painfully high frequency sound and you want to reduce the observed frequency of the sound by a proportion p, where 0

MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER A pulsar is a type of rotating neutron star that emits a beam of electromagnetic radiation. Imagine a pulsar that is moving toward Earth at a speed of 856.500 km/s. It emits mostly radio waves with a wavelength (at the source) of 132.500 cm. What is the observed wavelength of this radiation on Earth? (Assume the Earth is stationary. Consider the speed of light c = 3.00000 × 108 m/s. Give your answer to at least six significant figures.) 4.0 133 What relationship describes the frequency of a wave for an observer that is moving relative to the source? What is the relationship between frequency and wavelength? cm

My answer is incorrect, please write your explanation(process detail) why the answer is v(p)/(1-p) and write why my answer is wrong. I attach the image and write my process of explanation. My solution: When the source is moving away with a speed of vs. Using Doppler's effect for this case, f=fo(v/v+vs) Then the speed f source will be vs=(fo/f)-1v putting the values vs=(fo/pfo)-1v=1p-1v Hence, the speed of the source (moving away) is vs=1p-1v. Professor's solution and answer I attach in the image.

Please explain the steps to find the answer, which equation you are using and why you are using it. Also a small reflection about the problem.  Thanks.