A box of mass 27 kg is in the bed of a truck on a hill that is inclined at an angle of 26.1° above the horizontal. The tailgate of the truck is open. The truck is currently accelerating up the hill with a magnitude of 1.67 m/s2. What is the magnitude of the friction force from the truck on the box in this situation?
F= m a = 27 * 1.67
F = Ff - 27 * 9.81 * sin 26.1
so
Ff = 27 (1.67 + 9.81 sin26.1)