Question

bellringer

• imagine you are standing on a sidewalk and an ambulance drives past you with its siren on.
• how does the sound change as it moves toward you versus when it moves away?
• in science, light behaves similarly to sound. if a star is moving away from earth, do you think its light would appear more \blue\ (compressed) or more

ed\ (stretched)?

Explanation:

1. For the siren question: This is due to the Doppler effect, where sound waves compress as a source moves toward an observer, increasing frequency (higher pitch), and stretch as it moves away, decreasing frequency (lower pitch).
2. For the star question: Light follows the Doppler effect too. When a star moves away, its light waves are stretched to longer wavelengths, which correspond to the red end of the visible spectrum, a phenomenon called redshift.

Answer:

1. As the ambulance moves toward you, the siren has a higher, shriller pitch; as it moves away, the siren has a lower, deeper pitch.
2. The star's light would appear more "red" (stretched).