An engine approaches a hill with a constant s | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(D) Let the engine be at point $A$ initially and at point $C$ after $5 \, s$. The distance $AB = 0.9 \, km = 900 \, m$.The sound travels from $A$ to t

Vedclass · Accepted Answer

$30$

Vedclass · Answer

(D) Let the engine be at point $A$ initially and at point $C$ after $5 \, s$. The distance $AB = 0.9 \, km = 900 \, m$.The sound travels from $A$ to the hill at $B$ and reflects back to the engine at $C$.The total time taken $t = 5 \, s$ is the time taken by sound to travel the distance $AB + BC$.$t = \frac{AB}{v_{sound}} + \frac{BC}{v_{sound}}$$5 = \frac{900}{330} + \frac{BC}{330}$$5 	imes 330 = 900 + BC$$1650 = 900 + BC$$BC = 1650 - 900 = 750 \, m$.The distance traveled by the engine in $5 \, s$ is $AC = AB - BC = 900 \, m - 750 \, m = 150 \, m$.Therefore,the speed of the engine $v_{engine} = \frac{AC}{t} = \frac{150 \, m}{5 \, s} = 30 \, m/s$.

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 $5 \, s$. If the speed of sound in air is $330 \, m/s$,then the speed of the engine is .... $m/s$.

Similar Questions

The intensity of sound increases at night due to

An underwater sonar source operating at a frequency of $60 \, kHz$ directs its beam towards the surface. If the velocity of sound in air is $330 \, m/s$,the wavelength and frequency of waves in air are:

The following phenomenon cannot be observed for sound waves:

The wavelength of ultrasonic waves in air is of the order of

$A$ tuning fork of frequency $220 \,Hz$ produces sound waves of wavelength $1.5 \,m$ in air at $N.T.P$. The increase in wavelength when the temperature of air is $27^{\circ} C$ is nearly $\left(\sqrt{\frac{300}{273}}=1.05\right)$ (in $\,m$)

Vedclass Test Series

Exam Paper Generator

Online Exam Module