Answer:
In physics, a frame of reference, or reference frame, is a perspective that one uses to determine if an object is moving.
Explanation:
<span>The Balmer series or Balmer lines in atomic physics, is the designation of one of a set of six named series describing the spectral line emissions of the hydrogen atom. The Balmer series is calculated using the Balmer formula, an empirical equation discovered by Johann Balmer in 1885. this is all I know sorry</span>
True, recycling allows products to be reused which saves alot the natural resources that are used.
Entropy is the measure of the amount of disordered in a system.
<u>Explanation:</u>
In 1850, Entropy introduction by the German physicist Rudolf Clausius refers a measurement of the system's thermal energy in unit temperature. It is not for useful work because the work originates from ordered molecular motions. And, this also measures the molecular disturbance or randomness of the system.
The concept behind this provides deep view into spontaneous changes in many everyday phenomena’s. The idea of entropy is a mathematical way of coding an intuitive idea whose processes are impossible, and not violate the basic principle of energy conservation.
Answer:
The well is 7.1 meters deep.
Explanation:
The formula to use here is the distance in a uniformly accelerated motion:

where d stands for distance, t for time, a for acceleration, v0 and d0 for initial velocity and distance, respectively. Since the initial distance and velocity are both zero, we are left with the first term. The coin is in free fall and so it is accelerated by gravity:

The well is 7.1 meters deep.