Saved Bookmarks
| 1. |
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 sec. If the speed ofsound in air is 330 m/s, calculate the speed of the engine. |
|
Answer» Solution :If the speed ofthe ENGINE is V, the distance travelled by the engine in 5 SEC, will be 5V. And hence, the distance travelled by SOUND in reaching the HILL and coming back to the moving driver = 900 + (900 - 5V) =(1800 - 5V). So time interval between the original sound and its echo `(1800-5V)/330 = t = 5s` (given) The above equation on solving gives V = 30 m/s. |
|