Answer:
The minimum difference between the lengths of the two tubes should be 0.385 meters.
Explanation:
As we known that for any two waves to arrive in phase at any point the difference in the path traveled by the waves should be an integral multiple of the wavelength of the wave.
Mathematically we can write:

For the given wave we have

Applying values we get

Thus the minimum difference in the lengths of the tubes can be obtained by putting the value of n = 1

Answer:
Object in motion: By the Newton's first law about inertia, an object in motion tends to keep in motion, unless an external force act on it.
Object at rest: By the Newton's first law about inertia, an object at rest tends to keep at rest, unless an external force act on it.
Answer:
Position A/Position E
, 
Position B/Position D
,
, for 
Position C
, 
Explanation:
Let suppose that ball-Earth system represents a conservative system. By Principle of Energy Conservation, total energy (
) is the sum of gravitational potential energy (
) and translational kinetic energy (
), all measured in joules. In addition, gravitational potential energy is directly proportional to height (
) and translational kinetic energy is directly proportional to the square of velocity.
Besides, gravitational potential energy is increased at the expense of translational kinetric energy. Then, relative amounts at each position are described below:
Position A/Position E
, 
Position B/Position D
,
, for 
Position C
, 
Chemical changes are considered "unseen" because they change the chemical makeup, instead of the overall appearance.