Answer:
Coefficient of friction.
Explanation:
The amount of friction divided by the weight of an object is equal to the coefficient of friction. It is a dimensional less number. It can be given by :

N is normal force.
= coefficient of friction

The correct answer to go in the blank would be A) The particles are moving faster.
Answer:
As Per Provided Information
Moving body has 2m/s² acceleration
Time taken by body is 4 second
We are asked to find the 'change in velocity' ( ∆V) by the body.
<u>Formula Used here</u>

<u>Substituting </u><u>the </u><u>given </u><u>value</u>
<u>
</u>
<u>Therefore</u><u>,</u>
- <u>Change </u><u>in </u><u>velocity </u><u>is </u><u>8</u><u> </u><u>m/</u><u>s</u>