Ch10_1
New Problems
reloads the page with new variable values in all questions. You must do this after grading the test to rework it another time.
Make sure to calculate your answers in SI units unless specified otherwise .
1) The speed of sound in air is 343
m/s
. What is the wavelength of a sound wave that has a frequency of
Hz
(see sheet 3,3')
? Indicate with a positive (negative) sign whether the formula you use is only valid for sound waves (is valid for many waves, e.g. waves on a string, radio waves,...)
2) A sound source assumed to be a point emits a power of
W
. What is the sound intensity at a distance of
m
from the source
(see sheet 9.2)
?
3) You are at a distance of
m
from a point-like sound source and experience a sound intensity of
W/m
2
. How close to the source can you move before you experience a sound intensity of
W/m
2
, the pain threshold
(see sheet 9.2-9.4)
? Indicate with a positive (negative) sign whether for a large wall full of loudspeakers as the sound source you would experience the same (smaller increase) of the sound intensity upon approach.
4) A train approaches a station with
km/hr
and emits a whistle sound at
Hz
. What is the frequency registered at the station
(see sheet 12
,use 343
m/s
for the speed of sound
)
? Indicate with a negative (positive) sign whether the frequency registered at the station would be higher (lower) if the train moved away from the station.
5) A car speeds away with
km/hr
from a factory which emits a whistle sound at
Hz
. What is the frequency registered by the driver of the car
(see sheet 12
,use 343 m/s for the speed of sound
)
? Indicate with a negative (positive) sign whether the frequency registered would be higher (lower) if the car moved toward the station.
6) You approach a wall while emitting sound at
Hz
. The sound is reflected from the wall back at you and you register a reflected frequency of
Hz
. What is your speed
(see sheet 14,15
,use 343 m/s for the speed of sound
)
?
Once you have submitted your answers for grading by clicking the grade button, you
cannot resubmit answers
for the same Problem Set--you must use the 'New Problems' button first.