A box weighing 20 kg is pulled along a horizontal surface with a speed of 2 m/s by exerting a constant force of 50 N making an angle of 450 with the horizontal. Find the work done in moving the box through 12 m and the rate at which the work is done. Find also the work done against friction. What is the total work done in moving the box through 12 m ? mu = 0.2 .