Kinetic energy, KE, is modeled by the formula

, where m is the mass in kg and v is the velocity in m/s.
In this scenario, mass and one-half are constant but the velocity changes.
You can see that by squaring twice the velocity, that is equal to four times the original KE. Therefore, the answer is 4k.
I think that the answer is friction
<h3><u>Answer;</u></h3>
= 73 N
<h3><u>Explanation</u>;</h3>
Using the formula
2 T cos(30°) = w
Where; T is the tension on each string, while w is the weight of the box given by mg
Therefore;
W = 2Tcos 30°
= 2 × 42 cos 30°
= 84 cos 30°
= 72.74
<u> ≈ 73 N</u>
C. is the correct response.