Two progressive waves meet at a fixed point P. The variation with time of the displacement ofeach wave at point P is shown.210–1–20 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8displacement/ cmtime / sThe two waves superpose at point P.What is the resultant displacement at time 0.38 s?A +1.0 cm B –1.0 cm C +1.8 cm D –1.8 cm28 In which situation does diffraction occur?A A wave bounces back from a surface.B A wave passes from one medium into another.C A wave passes through a gap in a barrier.D Waves from two identical sources are superposed

A progressive wave equation is given as y=0.65sine1.2x -0.4t).Determine the period of the wave(ii) Determine the   wave velocitya.15.2seconds (ii) 0.333m/sb.15.7 seconds (ii) 0.333m/sc.16.7seconds (ii) 0.033m/sd.17.7 seconds (ii) 3.33m/se.2seconds (ii) 33.3m/s

(b) Sketch the graph of displacement against distance graph for progressive wave above ina range of 0 ≤ 𝑥 ≤ 𝜆 at time, t = 0 s.

22 A transverse water wave is moving along the surface of some water. This causes a ball to movevertically without moving horizontally as it floats upon the surface. At one instant, the ball is at theposition shown.2.4 m0.70 mballdirection ofwave travelNOT TOSCALEThe wave has a frequency of 0.20 Hz and an amplitude of 0.70 m. The distance between a troughand an adjacent peak is 2.4 m.What is the distance travelled by the ball in a time of 20 s?A 5.6 m B 9.6 m C 11.2 m D 19.2 m23 A sound wave travels from left to right across a room. The variation with distance across theroom of the displacement of the air molecules at one instant is shown.At which distance will the air pressure be lowest?displacementdistance from left-handend of roomrightleft0A B C D24 A source emits a sound wave of a single frequency. The Doppler effect causes a differentfrequency of sound to be heard by a stationary observer.What is a requirement for the Doppler effect to occur?A a source that is moving as it produces the sound waveB a source that produces a polarised sound waveC a source that produces a sound wave of changing amplitudeD a source that produces a sound wave of changing frequency

The solid line in the graph shows the variation with distance x of the displacement y of atravelling wave at t = 0. The dotted line shows the wave 0.20 ms later. The period of the waveis longer than 0.20 ms.6420– 2– 4– 60.20.0 0.4 0.8 1.00.6y / cmx / mPQ(a) (i) Calculate, in m s–1, the speed for this wave.

Two progressive waves meet at a point.Which condition must be met for superposition of the waves to occur?A The waves must be coherent.B The waves must be of the same type.C The waves must be travelling in opposite directions.D The waves must meet in phase.