a model rocket is made up of a shuttle of mass 20kg, and a fuel tank which has a mass of 4kg when it is empty. when the rocket attains an upwards velocity of 10m. per sec .all of its fuel is used up. At this point ,the empty tank is fired velocity to 13m. per sec .calculate the change in momentum of the rocket without empty fuel tank (60m. per sec upwards)​

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.