A projectile is fired with a velocity of 8 m/s at an angle of 65º. What is the vertical component of the velocity?
A. 6.5 m/s
B. 3.4 m/s
C. 10.2 m/s
D. 7.2 m/s

The net force acting on the box is zero.

In fact, the box does not move. According to Newton's second law, this means the resultant of the forces acting on the object is zero, because the acceleration of the object is zero:

This also means that the reaction of the wall against the box is equal to the force of 10 N that pushes the box, in order to balance it and have a net force of zero. On the vertical axis instead, the weight of the box (mg) is balanced by the normal reaction of the floor.