The sound level produced by one singer is
80.2 dB.
What would be the sound level produced
by a chorus of 19 such singers (all singing at
the same intensity at approximately the same
distance as the original singer)?
Answer in units of dB.

For general projectile motion, when the projectile is at the highest point of its trajectory, its acceleration is zero? a)the horizontal and vertical components of its velocity are zero. b) its velocity is perpendicular to the acceleration. c)the horizontal component of its velocity is zero. d)its velocity and acceleration are both zero.

With i really need the correct answer!

Diamond will scratch quartz. true or false