Two motors in a factory are running at slightly different rates. ...

[CORALGRILL2014]

Two motors in a factory are running at slightly different rates. One runs at 825.0 rpm and the other at You hear the sound intensity increase and then decrease periodically due to wave interference.
 
  How long does it take between successive instances of the sound intensity increasing?
  A) 1.79 s B) 1.43 s C) 1.54 s D) 1.66 s

Question 2

How many molecules are in (a) 1.0 cm3 of air at STP and (b) 1.0 cm3 of helium at STP? (R = 8.31 J/mol  K, NA = 6.022  1023 molecules/mol)
 
  What will be an ideal response?

[sierramartinez]

Answer to Question 1

C

Answer to Question 2

2.7  1019 molecules in both cases

[CORALGRILL2014]

Great answer, keep it coming

[adf223]

Excellent