**I really need help with 3, 4, and 5***
Rosa and Jon were asked by their physical science teacher to determine the speed of
sound. While walking to their dormitories af-
ter class, Jon clapped his hands, which Rosa
and Jon heard a moment later as an echo. The
echo bounced off a building that was 410 ft
away. They knew that they could not mea-
sure the brief time for a single clap to return,
so they had a brillant idea. Jon clapped and
then started to clap as soon as he heard the
echo, and he then continued this synchronized
clapping so that Rosa could measure the fre-
quency. Rosa counted 71 of Jon’s claps in one
half minute.
1) What is the frequency of Jon’s clapping? (2.37 Hz)
2) What is the speed of sound as determined by
Rosa and Jon?
Answer in units of ft/s. (1952.380952 ft/s)
3) Rosa and Jon decided to test their results, so
they walked an additional 190 ft away from
the wall.
What is the new clapping frequency?
Answer in units of Hz.
4) What is the new time between successive
claps?
Answer in units of s.
5) How many claps will Jon have to make in one
half minute?
Answer in units of claps.
Rosa and Jon were asked by their physical science teacher to determine the speed of
sound. While walking to their dormitories af-
ter class, Jon clapped his hands, which Rosa
and Jon heard a moment later as an echo. The
echo bounced off a building that was 410 ft
away. They knew that they could not mea-
sure the brief time for a single clap to return,
so they had a brillant idea. Jon clapped and
then started to clap as soon as he heard the
echo, and he then continued this synchronized
clapping so that Rosa could measure the fre-
quency. Rosa counted 71 of Jon’s claps in one
half minute.
1) What is the frequency of Jon’s clapping? (2.37 Hz)
2) What is the speed of sound as determined by
Rosa and Jon?
Answer in units of ft/s. (1952.380952 ft/s)
3) Rosa and Jon decided to test their results, so
they walked an additional 190 ft away from
the wall.
What is the new clapping frequency?
Answer in units of Hz.
4) What is the new time between successive
claps?
Answer in units of s.
5) How many claps will Jon have to make in one
half minute?
Answer in units of claps.
-
1. 71claps in 30s gives f = 71/30 = 2.37Hz
2. Distance travelled by sound between claps = 2 x 410 =820ft
Interval between claps = 30/71 = 0.4225s
Speed = d/t = 820/0.4225 = 1940.8 = 1940ft/s (disagree with your answer and you need to round to 3sig figs max)
3) Distance from wall = 190 + 410 = 600ft. Distance travelled by sound between claps = 1200ft.
Time between claps = time for sound to travel there and back = d/v = 1200/1940.8 = 0.6183s
Freq = 1/0.6183 = 1.62Hz
4) 0.618s (see above)
5) 1.62 claps per second for 30 second = 30 x 1.62 = 49 (to nearest clap)
2. Distance travelled by sound between claps = 2 x 410 =820ft
Interval between claps = 30/71 = 0.4225s
Speed = d/t = 820/0.4225 = 1940.8 = 1940ft/s (disagree with your answer and you need to round to 3sig figs max)
3) Distance from wall = 190 + 410 = 600ft. Distance travelled by sound between claps = 1200ft.
Time between claps = time for sound to travel there and back = d/v = 1200/1940.8 = 0.6183s
Freq = 1/0.6183 = 1.62Hz
4) 0.618s (see above)
5) 1.62 claps per second for 30 second = 30 x 1.62 = 49 (to nearest clap)