According to newton's first law, if an object is changing direction, what must be happening?
a. no force is acting on it.
b. a single force is acting on it.
c. balanced forces are acting on it.
d. unbalanced forces are acting on it.

Which sound characteristic is not affected by the relative motion of an object

What does si stand for,when referring to a system of measurement

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.