波的傳播

Questions 34 and 35 : The figure below shows the displacement-distance graph of a wave travelling to the right with speed $2\ \mathrm{cm\,s^{-1}}$ at a certain instant. $P$ and $Q$ are two particles at distances $x=8$ cm and $18$ cm respectively.

What is the period of the wave ?

Questions 34 and 35 : The figure below shows the displacement-distance graph of a wave travelling to the right with speed $2\ \mathrm{cm\,s^{-1}}$ at a certain instant. $P$ and $Q$ are two particles at distances $x=8$ cm and $18$ cm respectively.

What is the shortest time for $P$ to have the same displacement as $Q$ at the instant shown ?

Figure (a) shows a series of particles ($E$ - $O$) at their equilibrium positions. Figure (b) shows the positions of the particles at a certain instant when a longitudinal wave travelling to the right passes through the particles.

Which of the following statements is incorrect ?

A wave travels along a string to the left. The figure above shows its waveform at time $t=1$ s. Which of the following displacement-time graphs best represents the motion of particle $P$ ? (Take displacement upwards to be positive.)

Figure (a) shows the equilibrium positions of particles $E$ to $N$ in a medium. A longitudinal wave is travelling from left to right. At time $t_1$, the positions of the particles are shown in Figure (b).

Which of the following particles is momentarily at rest at $t_1$ ?

Figure (a) shows a series of particles ($a$ - $k$) at their equilibrium positions. Figure (b) shows the positions of the particles at a certain instant when a longitudinal wave travels to the right passes through the particles. Which are the directions of the motion of particles $c$ and $f$ at the instant shown in Figure (b) ?

Figure (a) shows a series of particles which is uniformly distributed along a slinky spring. Figure (b) shows their positions at a certain instant when a travelling wave passes through the slinky spring from left to right. Which of the following diagrams shows the correct positions of the particles after half a period from the instant shown in Figure (b) ?

A longitudinal wave is travelling from left to right in a medium. Figure (a) shows the equilibrium positions of particles $A$ to $J$ in the medium. At time $t=0$, the positions of the particles are shown in Figure (b). Which of the following correctly shows the displacement-time graph of particle $I$ ? (Note : displacement to the right is taken to be positive.)

In December 2004, an earthquake in the Indian Ocean caused a tsunami which produced water waves having wavelength about $100$ m and frequency about $2$ Hz. What was the approximate time taken for these water waves to travel from the earthquake centre to Sri Lanka across a distance of about $1500$ km ?