A system's initial internal energy is 27 J. Then heat is added to the system. If the final internal energy is 34 J and the system does 26 J of work, how much heat is added to the system?

Place me with this question is my last question

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.

Find the mass by adding the numbers from the three sliders