ELASTIC WAVES AND SOUND I.I.S. “BERETTA” – LICEO SCIENTIFICO “MORETTI” From Finland CLIL PHYSICS: To Italy Through

A wave has two main characteristics: 1. it is a travelling energy/disturbance; 2. it carries energy/disturbance from one place to another. the nature of waves We will consider two basic types of waves: For transverse/longitudinal waves: the direction of the disturbance (displacement) is perpendicular/parallel to the direction of wave motion. 1) Choose the correct word:

Transverse and longitudinal waves are called ………….. waves because they consist of regularly repeating …………….. that are produced over and over again by the …………. periodic waves: spatial dependence Example: draw a transverse momentum wave and define the amplitude and wavelength. These definitions also apply to longitudinal waves. The ……………………….. is the maximum ……………………… of a particle from its undisturbed ……………………... In the diagram, a single of the wave is highlighted in colour. A wave is a …………… of these repeating cycles. The …………………………….. is the spatial period of the wave in the direction of motion: the horizontal …………………. of one cycle of the wave or the distance between any two ……………………………. points with the same phase. 2) Fill in each gap the correct word from the list: position, patterns, amplitude A, periodic, successive, length,series, source, displacement, wavelength λ, cycle

A ………………… can be described as a function of ……………….. by observing the change in displacement of a ……………………….. point on the wave. As the wave passes, the point under observation oscillates in ………………. harmonic. periodic waves: time dependence The period T [s] is the time …………….. for ……………. complete cycle. It is related to the ………………… by: f = 1/T [Hz]. For any periodic wave, the …………………..between period, wavelength, and speed is given by: This relationship applies to longitudinal ………………… to transverse waves. 3) Fill in each gap the correct word from the list: simple, required, as well as, one, relationship, time, single, wave, frequency.

Sound is carried …….. longitudinal waves that are created ……. vibrating objects, such ……. a guitar string …… human vocal cords, or the diaphragm ……. a loudspeaker. A sound can be made ……. of several overlapping waves with different frequencies. A sound …….. a single frequency is called a pure tone. Sound can be created or transmitted only …… a medium, such as a gas, liquid, …… solid. Sound cannot propagate ….. a vacuum. the nature of sound Sound has an associated frequency, which is the number of cycles ….. second passing a given location. 4) Complete the text: the, or, by (2), with, as, up, of, in (2), per.

Sound travels through …………………………………………………………………………… The speed of wave depends on ………………………………………………………………… the speed of sound substancespeed (m/s) gases air (20 °C)343 helium (0 °C)965 liquid mercury (20 °C)1,450 seawater (20 °C)1,522 solid copper5,010 glass (pyrex)5,640 steel5,960 The speed of sound and the speed of light 5) Working in pairs, discuss the table and the picture: The speed of light is ……………………………… Therefore, lightning and thunder …………………

learning the basics TF 1.You can hear only when vibrations are produced by your vocal cords. 2.Both longitudinal and transverse waves are characterised by an amplitude and a frequency. 3.Sound can be created in or transmitted through a gas, liquid, solid or vacuum. 4.Ultrasound wave has a greater wavelength than acoustic wave. 5.Thunder reaches the observer well before than lightning. 6) Decide if the following statements are true or false:

language practice 7) Match the hints in column one to the terms in column two: 1.A travelling disturbance that carries energy from one place to another. 2. The maximum displacement of a particle from its rest position. 3. The spatial period of a wave in the direction of its motion. 4. A mechanical disturbance of the particles in a solid, liquid, or gaseous medium. 5. The number of oscillatory cicles per second. ABCDEABCDE Wavelenght Elastic wave Frequency Wave Amplitude