Browse by Stream
QnA
Home
QnA
Go To Your Study Dashboard

Get Answers to all your Questions

header-bg qa
  • Home
  • Engineering
  • An engine approaches a hill with a constant speed. When it is at a distance of 0.9 km, it blows a whistle whose echo is heard by the driver after 5 seconds. If the speed of sound in air is 330 m/s,

An engine approaches a hill with a constant speed. When it is at a distance of 0.9 km, it blows a whistle whose echo is heard by the driver after 5 seconds. If the speed of sound in air is 330 m/s, then the speed of the engine is : 

Option: 1

32 m/s


Option: 2

27.5 m/s


Option: 3

60 m/s 


Option: 4

30 m/s


Answers (1)

best_answer

If the speed of engine is v, the distance travelled by engine in 5s will be 5v and hence the distance travelled by sound in reaching the hill and coming back to the moving driver

\begin{aligned} &=900+(900-5 v)\\ &1800-5 v \end{aligned}

So, the time interval between original sound and it's echo

t=\frac{(1800-5 v)}{330}=5 \Rightarrow v=30 m / s

Posted by

shivangi.shekhar

View full answer

JEE Main high-scoring chapters and topics

Study 40% syllabus and score up to 100% marks in JEE

Similar Questions

Trending Articles/News

anam-khan

BTech 2025 Admission LIVE: JoSAA revised schedule out on josaa.nic.in; updates on MHT CET, KEAM counselling
anam-khan

Andhra launches free JEE, NEET coaching to over 1 lakh govt school students
anam-khan

JoSAA Counselling 2025 LIVE: BTech registration starts at josaa.nic.in for IIT, NIT, IIIT admissions

Latest Question