On a long horizontally moving belt, a child runs to and fro with a speed $9\, km\, h^{-1}$ (with respect to the belt) between his father and mother located $50\, m$ apart on the moving belt. The belt moves with a speed of $4\, km\, h^{-1}$. For an observer on a stationary platform, the speed of the child running in the direction of motion of the belt is ..... $km\,h^{-1}$
Medium
Download our appand get started for free
Experience the future of education. Simply download our apps or reach out to us for more information. Let's shape the future of learning together!No signup needed.*
Similar Questions
- 1View SolutionThe waves in which the particles of the medium vibrate in a direction perpendicular to the direction of wave motion is known as
- 2$4.0 \,g$ of a gas occupies $22.4$ litres at $NTP.$ The specific heat capacity of the gas at constant volume is $5.0 \,\,J K^{-1} mol^{-1}$. If the speed of sound in this gas at $NTP$ is $952\, m s^{-1}$, then the heat capacity at constant pressure is .... $J K^{-1} mol^{-1}$ (Take gas constant $R = 8.3 \,\,J K^{-1} mol^{-1}$)View Solution
- 3A block $\mathrm{M}$ hangs vertically at the bottom end of a uniform rope of constant mass per unit length. The top end of the rope is attached to a fixed rigid support at $O$. A transverse wave pulse (Pulse $1$ ) of wavelength $\lambda_0$ is produced at point $O$ on the rope. The pulse takes time $T_{O A}$ to reach point $A$. If the wave pulse of wavelength $\lambda_0$ is produced at point $A$ (Pulse $2$) without disturbing the position of $M$ it takes time $T_{A 0}$ to reach point $O$. Which of the following options is/are correct?View Solution
(image)
[$A$] The time $\mathrm{T}_{A 0}=\mathrm{T}_{\mathrm{OA}}$
[$B$] The velocities of the two pulses (Pulse $1$ and Pulse $2$) are the same at the midpoint of rope.
[$C$] The wavelength of Pulse $1$ becomes longer when it reaches point $A$.
[$D$] The velocity of any pulse along the rope is independent of its frequency and wavelength.
- 4A pipe of length $1.5\ m$ closed at one end is filled with gas and resonates in its fundamental mode with a tuning fork. Another open organ pipe of same dimensions filled with air resonates in its fundamental mode with same tuning fork. If experiment is performed at $30\,^oC$ (speed of sound in air is $360\ m/sec$ at $30\,^oC$), the speed of sound at $0\,^oC$ in gas is ...... $m/sec$ (Neglect end correction)View Solution
- 5The figure represents the instantaneous picture of a longitudinal harmonic wave travelling along the negative $x$-axis. Identify the correct statement $(s)$ related to the movement of the points shown in the figure. The stationary points areView Solution
- 6$41$ forks are so arranged that each produces $5$ beats per sec when sounded with its near fork. If the frequency of last fork is double the frequency of first fork, then the frequencies of the first and last fork are respectivelyView Solution
- 7One end of a taut string of length $3 \ m$ along the $x$-axis is fixed at $x=0$. The speed of the waves in the string is $100 \ m / s$. The other end of the string is vibrating in the $y$-direction so that stationary waves are set up in the string. The possible waveform$(s)$ of these stationary waves is (are)View Solution
$(A)$ $y(t)=A \sin \frac{\pi x}{6} \cos \frac{50 \pi t}{3}$
$(B)$ $y(t)=A \sin \frac{\pi x}{3} \cos \frac{100 \pi t}{3}$
$(C)$ $y(t)=A \sin \frac{5 \pi x}{6} \cos \frac{250 \pi t}{3}$
$(D)$ $y(t)=A \sin \frac{5 \pi x}{2} \cos 250 \pi t$
- 8The power of sound from the speaker of a radio is $20$ milli watt by turning the knob of the volume control the power of the sound is increased to $400$ milli watt. The power increase in decibles as compared to the original power is ..... $dB$View Solution
- 9The equation $\overrightarrow {\phi \,} (x,\,t) = \overrightarrow {j\,} \sin \,\left( {\frac{{2\pi }}{\lambda }v\,t} \right)\cos \,\left( {\frac{{2\pi }}{\lambda }x} \right)$ representsView Solution
- 10A person driving car at a constant speed of $15\,m / s$ is approaching a vertical wall. The person notices a change of $40\,Hz$ in the frequency of his car's horn upon reflection from the wall. The frequency of horn is ............ $Hz$. (Given : Speed of sound : $330\,m / s$ )View Solution