Answer:
option a is correct
Explanation:
<h2>I hope it's help you ❣️❣️</h2>
Answer:
The speed is 24 
Explanation:
A wave is a disturbance that propagates through a certain medium or in a vacuum, with transport of energy but without transport of matter.
The wavelength is the minimum distance between two successive points of the wave that are in the same state of vibration. It is expressed in units of length (m).
Frequency is the number of vibrations that occur in a unit of time. Its unit is s⁻¹ or hertz (Hz).
The speed of propagation is the speed with which the wave propagates in the middle, that is, the magnitude that measures the speed at which the wave disturbance propagates along its displacement. Relate wavelength (λ) and frequency (f) inversely proportionally using the following equation:
v = f * λ.
In this case, λ= 8 meter and f= 3 Hz
Then:
v= 3 Hz* 8 meter
So:
v= 24 
<u><em>The speed is 24 </em></u>
<u><em></em></u>
To develop this problem it is necessary to apply the concepts related to Gravitational Potential Energy.
Gravitational potential energy can be defined as

As M=m, then

Where,
m = Mass
G =Gravitational Universal Constant
R = Distance /Radius
PART A) As half its initial value is u'=2u, then



Therefore replacing we have that,

Re-arrange to find v,



Therefore the velocity when the separation has decreased to one-half its initial value is 816m/s
PART B) With a final separation distance of 2r, we have that

Therefore




Therefore the velocity when they are about to collide is 
All ions are atoms with a charge