While unloading furniture, a worker slides a heavy box down the ramp on the rope. The ramp is inclined 6o degree to the horizontal and the worker applies upward force of 450N parallel to the ramp to move the box without acceleration. If the coefficient of kinetic friction between the ramp and the box is 0.25, find mass of the box?

Hint - start by drawing a free body diagram of the box with the forces of the rope, the component of the box's weight in the direction of the ramp, and the friction force. These must add to zero (otherwise the box would accelerate rather than move at a constant velocity). What do you get?