Question

Rank the size of the Doppler shift from largest to smallest for light from each star A-E.

a) A, B, C, D, E
b) E, D, C, B, A
c) B, E, A, C, D

Answer 1

The ranking of the Doppler shift from smallest to largest, based on the stars' motion relative to Earth, is Star A (smallest), Star C, and then Star B (greatest). Options provided in the question do not match the scenario described.

Step-by-step explanation:

The question pertains to the Doppler shift of light from stars. The Doppler shift is greatest when the star is moving directly away from or towards the observer. In the given scenario, with stars moving at 100 km/s:

• Star A, moving perpendicular to our line of sight, would show the smallest Doppler shift, because there is no component of its velocity in the line-of-sight direction.
• Star B, moving directly away from the Earth, would show the greatest Doppler shift, as all its motion contributes to the line-of-sight velocity.
• Star C, moving at a 30° angle to the line of sight, would experience a Doppler shift smaller than Star B but greater than Star A because only part of its velocity is directed along the line of sight.

Hence, the ranking from the smallest to the greatest Doppler shift is Star A, C, B. The options provided (a, b, c) in the question do not match the scenario provided, as Star D and Star E are not described in the scenario.