Answer:
the acceleration of the box is 3.2[m/s^2]
Step-by-step explanation:
This problem can be solved using the second law of movement, described by Newton. Which says that the sum of forces on a body must be equal to the product of its mass by the acceleration of it if the body is not in static equilibrium. Therefore:
![F-f=m*a\\where:\\F=25[N]\\f=2.6[N]\\m= 7[kg]\\replacing:\\25-2.6=7*a\\a=3.2[m/s^2]](https://img.qammunity.org/2020/formulas/physics/middle-school/t7ekfwz07ngmy93i6p1z37su1tz2kje70g.png)
Note: the only force that is opposite to the movement is the friction force, therefore, this force takes the minus sign