sound waves

what is a sound wave?

vibration of air molecules

what is the range of human hearing? what is part of the explanation for this?

20Hz → 20000Hz

sound waves can trigger vibrations in solids, but only works over a limited range of frequencies

what can change as a wave moves from one medium to another?

their speed, and because of v = f x w, the wavelength changes too

what do sound waves travel the fastest in? why?

solids as the particles in solids are very close together so they can pass vibrations between them more easily

what does not change when a wave enters a new medium? why?

the frequency - the waves would have to be created or destroyed at the boundary, and that is not possible

how does pitch change with frequency?

higher the frequency, higher the pitch

what changes with amplitude? how?

sound/volume - larger amplitude means higher volume

why do soundwaves only travel through a medium?

sound waves move by particles vibrating and, so if there are no particles sound waves cannot travel

how is sound transmitted through a medium?

they transfer the sound energy via the particles vibrating and knocking into other particles

what is a reflected sound wave called?

an echo

what is ultrasound?

sound that is higher in frequency than the limit of human hearing - at least 20,000Hz

what is special about ultrasound?

it partially reflects at the boundary between two different densities

what can ultrasound scanners do?

produce images of internal organs, such as the kidney or heart, industrial imaging, echo sounding to calculate depth of water

why is ultrasound safer than x-rays?

ultrasound does not cause mutations, and does not increase risk of cancer

what is equation for determining distance using ultrasound?

s = v x t

distance = speed x time