Explanation:
You need two, maybe three things - something that's vibrating, a medium for those vibrations to propagate in, and a listener to hear it or recording equipment to pick it up
Answer:
He sees the ball coming at him at 150 km/hr.
Explanation:
In Newtonian physics, the observer would say that the velocity of the first object is the sum of the two velocities.
Due to the same direction, both velocities will be added.
Well, in some systems the atoms melt or burn or change state like from liquid to gases when they reach a certain temperature. This could decrease the energy in the system.
Hope I helped
