A force diagram shows a box accelerating to the right on a horizontal surface of negligible friction. The tension T is exerted at an angle of 30° above the horizontal. If μ is the coefficient of kinetic friction between the box and the surface, what is a correct mathematical equation derived by applying Newton’s second law to the box? Note: The force of friction f is equal to the coefficient of friction multiplied by the normal force N.

A force diagram shows a box accelerating to the right on a horizontal surface of negligible friction. The tension T is exerted at an angle of 30° above the horizontal. If μ is the coefficient of kinetic friction between the box and the surface, what is a correct mathematical equation derived by applying Newton’s second law to the box? Note: The force of friction f is equal to the coefficient of friction multiplied by the normal force N.