I'm pretty sure that it's 815.
Answer A is incorrect
A crest is just one point. It is not the distance between 2 crests.
B is incorrect
A trough is just 1 point. It is not the distance between 2 troughs.
C is incorrect.
the amplitude measures the height of a crest from the middle of the wave to the crest (or trough).
D is the correct answer. That is the distance between 2 crests or 2 troughs
1) True 2) True 3)True I hope I helped
Answer:Shifted towards Left by distance of 2.243 m
Explanation:
Given
Mass of john 
Mass of barbara 
John is standing at 
Barbara is standing at 
Now if they change their Position then
Thus we can see that center of mass shifted towards left by a distance of 
because heavier is shifted towards left
