A person can hear an echo 0.11 sec. after he souted near a hill. If the speed of sound in air is 332 m/s, calculate the distance between the person and the hill.
Share
A person can hear an echo 0.11 sec. after he souted near a hill. If the speed of sound in air is 332 m/s, calculate the distance between the person and the hill.
Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Answer:
Let d be the distance of first hill , which gives an echo after 3/2s and d
′
be the distance of another hill which gives echo after 5/2s , from the person .
given , speed of sound =332m/s
now for echo from first hill ,
total distance travelled by sound =2d , (distance is doubled as the sound comes back to person after reflection)
total time taken by sound =3/2s , to travel a distance of 2d,
hence , distance=speed×time ,
2d=332×(3/2) ,
or d=249m ,
for echo from another hill ,
total distance travelled by sound =2d
′
, (distance is doubled as the sound comes back to person after reflection)
total time taken by sound =5/2s , to travel a distance of 2d
′
,
hence , distance=speed×time ,
2d
′
=332×(5/2) ,
or d
′
=415m ,
therefore total distance between hills =249+415=664m .
Third echo will be heard when sound coming to person after reflection from first hill (first echo) goes toward another hill and reflects back to person again ,
time taken by sound to reflect back to person from first hill (first echo) =3/2s ,
time taken by sound to reflect back to person from another hill =5/2s ,
therefore , total time (for third echo) =(3/2)+(5/2)=4s .
Hi blink:-):-)