JAMB - Physics (1983 - No. 8)
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?
10m
125m
175m
350m
1,000m
설명
Difference in time = 1 sec.
echo time = 1 \(\div\) 2 = 0.5 sec.
= 0.5 x 250
= 125m
echo time = 1 \(\div\) 2 = 0.5 sec.
= 0.5 x 250
= 125m