The expanding universe

Question 1

What is the doppler effect?

Answer 1

change of frequency of sound (or light) waves moves relative to the observer

Question 2

When source of sound moves toward observer?

Answer 2

more sound waves heard per second so frequency is increased (and u take away in the equation as distance is less)

Question 3

When source of sound moves away observer?

Answer 3

less sound waves heard per second so frequency is decreased

Question 4

Function of the Doppler effect?

Answer 4

measure the speed at which distant galaxies are moving relative to the Earth
measure the speed of blood flow using ultrasound waves.