Answer:
Explanation:
This problem is approached using Coulomb's law of electrostatic attraction which states that the force F of attraction or repulsion between two point charges, 
and 
is directly proportional to the product of the charges and inversely proportional to the square of their distance of separation R.
where k is the electrostatic constant.
We can make k the subject of formula as follows;
Since k is a constant, equation (2) implies that the ratio of the product of the of the force and the distance between two charges to the product of charges is a constant. Hence if we alter the charges or their distance of separation and take the same ratio as stated in equation(2) we will get the same result, which is k.
According to the problem, one of the two identical charges was altered from 
to 
and their distance of separation from 
to 
, this also made the force between them to change from 
to 
. Therefore as stated by equation (2), we can write the following;
Therefore;
From equation (4) we now make the new force the subject of formula as follows;
then cancels out from both side of the equation, hence we obtain the following;
From equation (4) we can now write the following;
This could also be expressed as follows;
When undergoing an ultrasound, the transducer probe of the ultrasound machine transmits sound waves. It also receives the sound waves that are reflected back after it reaches a boundary.
The reflected waves are received by the probe and relayed to the ultrasound machine. The machine calculates the distance from the probe to the tissue or organ (boundaries) using the speed of sound in tissue and the time of the each echo's return. It then <span>displays the distances and intensities of the echoes on the display screen, forming a two dimensional image. </span>
I think it is B as 168/20
Answer:
average speed = total distance/total time
