30km. 24 the first two hours and 6 the half hour
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:

Answer:
This is an open circuit
Explanation:
An open circuit I believe
It needs to be closed for the bulb to be turned on
Surface air pressure is a consequence of the weight of the air acting on its surface. For example, if you are standing on Mars, the pressure around you is what you call the surface air pressure. Thus, that surface air pressure must be 0.007 atm.