In phase would mean both waves are at a positive peak, out of phase would mean one is at a positive whilst the other is at a negative. Out of phase would mean the waves cancel each other out
Answer :
(-3.7 meter/second) - (13.9 meter/second) = -17.6 meter/second
(21.4 second) - (72 second) = -50.6 second
Explanation :
(1) As we are given the expression :
(-3.7 meter/second) - (13.9 meter/second)
Now we have to evaluate this expression, we get:
⇒ -17.6 meter/second
(2) As we are given the expression :
(21.4 second) - (72 second)
Now we have to evaluate this expression, we get:
⇒ -50.6 second
Answer:

Explanation:
When teacher falls into the cliff then she shout for Help at the same time
so here we know that sound will go down and reflect back up
so here in 3 s distance traveled by the sound



now in the same time the distance that teacher will fall down is given as



now total distance traveled by teacher and sound in 3 s


this total distance must be equal to twice the height of the cliff


Answer: Having Pure Water Is Zero.
Explanation: ...