<span>A cold front separates a cold, dry air mass from a warm air mass.</span>
By conducting exhaustive, high-intensity online research for about 15 seconds, I found a source that says the speed of sound in copper is 4600 m/s. (You could easily have completed the same research project in about 1/3 of the time it took you to type and post the question here.)
Time it takes = (distance) / (speed)
Time = (25,000 meters) / (4600 m/s)
Time = (25 / 4.6) km-sec/km
<em>Time = 5.43 seconds </em>
6050 J is the kinetic energy at D
<u>Explanation:</u>
In physics, the object's kinetic energy (K.E) defined as the energy it possesses during movement. It can be defined as the required work to accelerate a certain body weight in order to rest at a certain speed. When the body receives this energy as it speeds up (accelerates), it retains this energy unless speed varies. The equation is given as,

Where,
m - mass of an object
v - velocity of the object
Here,
Given data:
m = 100 kg
v = 11 m/s
By substituting the given values in the above equation, we get

Dipper effect of an oncoming train get louder as it approaches and sound diminishes as it goes away sound traveling
As a system is cooled to its freezing point, the kinetic energy of the particles in the system will lower so the movement are much slower. Cooling means taking out heat from the system. This process is a physical change because it is only the phase of the system is changed and it is still the substance after the process.