Answer:

Explanation:
The amplitude of he combined wave is:

A, is the amplitude from the identical harmonic waves
B, is the amplitude of the resultant wave
θ, is the phase, between the waves
The amplitude of the combined wave must be 0.6A:

Set up a proportion
1 mile/1.6 km = 20,000miles/x
Cross Multiply
x = (20,000) * (1.6)
x = 32,000 kilometers
Answer:
Yes
Explanation:
If lamp A burnt out there would still be a wire above it that connects lamp B and C to the power source
Answer:
The relative velocity of an object A with respect to another object B.
Explanation:
The relative velocity of an object A with respect to another object B is the velocity that object A would appear to have to an observer situated on object B moving along with it.