The 1.2-Mg steel beam is moved over a level surface using a series of 30-mm-diameter rol...

The 1.2-Mg steel beam is moved over a level surface using a series of 30-mm-diameter rollers for which the coefficient of rolling resistance is 0.4 mm at the ground and 0.2 mm at the bottom surface of the beam. Determine the horizontal force P needed to push the beam forward at a constant speed. Hint: Use .the result of Prob. 8-140.