ork done in pushing a crate Sarah pushes a heavy crate 3.0 m along the floor at a constant speed. She pushes with a constant horizontal force of magnitude 70 N. How much work does Sarah do on the crate? Known F = 70 N d = 3.0 m v = constant Find After W TE Before 12 à By pushing on the crate Sarah increases its kinetic energy. so it makes sense that the work done is positive. AFE Example 10.2 Work done in pulling a suitcase A strap inclined upward at a 45° angle pulls a suitcase through the airport. The tension in the strap is 20 N. How much work does the tension do if the suitcase is pulled 100 m at a constant speed? Before: After: Ө Known T= 20 N 0=45° d = 100 m Find W d X it makes sense that the work is positive. The work done goes entirely into increasing the thermal energy of the suitcase and the floor.
