# Waves Speed Problem

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

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hage567
Homework Helper
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.

so that mean the first question is right!

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

frequency= 1/0.25= 4 hz

am i right?

hage567
Homework Helper
for pulses question it will be:
period= 4/16=0.25 pulses

frequency= 1/0.25= 4 hz

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

yep thank you