IB Physics HL C.2 practice question

Question 1

Paper 2Hard10 marks

A cord and a spring each carry a sinusoidal travelling disturbance along the equilibrium $x$ -axis. Figure 1 shows the displacement of particles from equilibrium at $t=0$ and $t=0.20\ \mathrm{s}$ plotted against each particle’s equilibrium coordinate $x$ In the upper panel, $y$ is the cord-particle displacement perpendicular to $x$ with positive $y$ upwards. In the lower panel, $u$ is the spring-particle displacement along $x$ with positive $u$ in the $+x$ direction. Each disturbance retains its profile as it travels.

(a)

Determine the direction of propagation and the speed of the disturbance on the cord.

[2]

(b)

State the wavelength of the disturbance on the cord.

[1]

(c)

At $x=0.20\ \mathrm{m}$ determine the instantaneous velocity of the cord particle at $t=0.20\ \mathrm{s}$ Give your answer with its direction.

[4]

(d)

The spring disturbance is now launched in the opposite direction, with its speed and wavelength unchanged. Describe how its profile at $t=0.20\ \mathrm{s}$ is displaced relative to its profile at $t=0$ State whether the disturbance is still longitudinal, and explain your answer.

[3]

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