# Waves Problem

1. Feb 24, 2007

### pharaoh

A periodic longitudinal wave that has a frequency of 20.0 Hz travels along a coil spring. If the distance between successive compressions is 0.400 m, what is the speed of the wave?

T=1/f
T=1/20=0.05 sec

v=d/t= 0.400 meter/ 0.05 second= 8 m/s

there is other question but i couldn't figure it out because i don't know how i can use pulses to get frequency or period

the question is

A wave generator produces 16.0 pulses in 4.00 s.
a. What is its period?

b. What is its frequency?

can i know what pulse really mean, and if i am right by saying frequency will be 16/2=8 hertz

2. Feb 24, 2007

### hage567

Your answer for for the second problem isn't quite correct. Why are you dividing by 2 and not 4?

See here http://en.wikipedia.org/wiki/Pulse_wave for what a pulse wave looks like. The definition of frequency remains the same, it is still how many cycles you get per unit time.

3. Feb 24, 2007

### pharaoh

so that mean the first question is right!

4. Feb 24, 2007

### pharaoh

for pulses question it will be:
period= 4/16=0.25 pulses

frequency= 1/0.25= 4 hz

am i right?

5. Feb 24, 2007

### hage567

Period = 0.25 is correct, but "pulses" is not a unit. You mean "seconds" there, right?
The frequency is correct.

6. Feb 24, 2007

### pharaoh

yep thank you