Topic 4 - Waves - Measuring Velocity

Question 1

How can you measure the velocity of sound in air?

Answer 1

Make a noise at ~50m from a solid wall and record the time for the echo to be heard, then use speed = distance/time.

Question 2

What method can be used to measure the velocity of sound using two microphones?

Answer 2

Have two microphones connected to a datalogger at a large distance apart and record the time difference between a sound passing from one to the other, then use speed = distance/time.

Question 3

How can ripples on a water surface be used to measure velocity?

Answer 3

Use a stroboscope that has the same frequency as the water waves and measure the distance between the ‘fixed’ ripples, then use v = fa.

Question 4

What is the formula for calculating speed from wavefront measurements?

Answer 4

Speed = distance/time.

Question 5

Fill in the blank: To measure the velocity of ripples, you can move a pencil along the paper at the same speed as a wavefront and measure the time taken to draw this line and the length of the line, then use speed = _______.

Answer 5

distance/time