A50.0-kg box is being pulled along a horizontal surface by means of a rope that exerts a force of 250 n at an angle of 32.0° above the horizontal. the coefficient of kinetic friction between the box and the surface is 0.350. what is the acceleration of the box?

According to Newton's second law, the resultant of the forces acting on the box is equal to the product between its mass and its acceleration:
(1)

we are only concerned about the horizontal direction, so there are only two forces acting on the box in this direction:
- the horizontal component of the force exerted by the rope, which is equal to

- the frictional force, acting in the opposite direction, which is equal to


By applying Newton's law (1), we can calculate the acceleration of the box: