water in an electric kettle is brought to boil in 180s by raising its temperature from 20°c to 100°c. it then takes a further 1200s to boil the kettle dry. calculate the specific latent heat of vaporisation of water, l,at 100°c. the specific heat capacity of water is 4200j/kg/k.
state any assumptions made.

Two loudspeakers, 5.5 m apart and facing each other, play identical sounds of the same frequency. you stand halfway between them, where there is a maximum of sound intensity. moving from this point toward one of the speakers, you encounter a minimum of sound intensity when you have moved 0.33 m . assume the speed of sound is 340 m/s.part a) what is the frequency of the sound? part b) if the frequency is then increased while you remain 0.21 m from the center, what is the first frequency for which that location will be a maximum of sound intensity? express your answer to two significant figures and include the appropriate units.