To find the magnitude of the acceleration of the box, we can use Newton's second law of motion. According to the second law, the net force acting on an object is equal to the product of its mass and acceleration.
In this case, the horizontal force applied to the box is 340 N, and the force of kinetic friction opposing the motion is 150 N.
The net force acting on the box is the difference between the applied force and the force of friction:
Net force = Applied force - Force of friction
= 340 N - 150 N
= 190 N
Now, we can calculate the acceleration of the box using Newton's second law:
Net force = Mass x Acceleration
Rearranging the formula to solve for acceleration:
Acceleration = Net force / Mass
= 190 N / 68 kg
โ 2.79 m/s^2
Therefore, the magnitude of the acceleration of the box is approximately 2.79 m/s^2.