A ship travelling towards a cliff receives the echo of its whistle after 3.5 seconds. A short while later, it receives the echo after 2.5 seconds. If the speed of sound in air under the prevalling condition is 250ms -1, how much closer is the ship to the cliff?
A
10m
B
350m
C
175m
D
125m
Verified Correct Answer: D.
Physical Principles & Numerical Solution
Difference in time = 1 sec
echo time = 1 \(\div\) 2 = 0.5 sec
Difference of cliff from ship = 0.5 x 250
= 125m
Source: Myschool Past Questions Archive (Record #56915)