Sand is made of tiny pieces of rock that have been worn down by wind and water. explain why the formation of sand is a physical change.

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.

Which of the following is not an appropriate unit for acceleration? (kg/12 mihr? m/min/sec cm/30c?

Match each type of lever with the correct diagram. 1. first-class 2. third-class 3. second-class