DP Physics (last assessment 2024)

Question 19N.2.SL.TZ0.3

Date	November 2019	Marks available	[Maximum mark: 7]	Reference code	19N.2.SL.TZ0.3
Level	SL	Paper	2	Time zone	TZ0
Command term	Calculate, Draw, Explain, State	Question number	3	Adapted from	N/A

[Maximum mark: 7]

19N.2.SL.TZ0.3

The solid line in the graph shows the variation with distance $x$ of the displacement $y$ of a travelling wave at t = 0. The dotted line shows the wave 0.20 ms later. The period of the wave is longer than 0.20 ms.

(a(i))

Calculate, in m s^–1, the speed for this wave.

[1]

Markscheme

v = « $\frac{0.05}{0.20 \times 10^{- 3}} =$ » 250 «m s^–1»✔

(a(ii))

Calculate, in Hz, the frequency for this wave.

[2]

Markscheme

λ = 0.30 «m» ✔
$f$ = « $\frac{250}{0.30} =$ » 830 «Hz» ✔

NOTE: Allow ECF from (a)(i)
Allow ECF from wrong wavelength for MP2

(b)

The graph also shows the displacement of two particles, P and Q, in the medium at t = 0. State and explain which particle has the larger magnitude of acceleration at t = 0.

[2]

Markscheme

Q ✔
acceleration is proportional to displacement «and Q has larger displacement» ✔

One end of a string is attached to an oscillator and the other is fixed to a wall. When the frequency of the oscillator is 360 Hz the standing wave shown is formed on the string.

Point X (not shown) is a point on the string at a distance of 10 cm from the oscillator.

(c(i))

State the number of all other points on the string that have the same amplitude and phase as X.

[1]

Markscheme

3 «points» ✔

(c(ii))

The frequency of the oscillator is reduced to 120 Hz. On the diagram, draw the standing wave that will be formed on the string.

[1]

Markscheme

first harmonic mode drawn ✔

NOTE: Allow if only one curve drawn, either solid or dashed.