A baseball player at practice is pushing a tackling dummy across the field. He initially has to push the 130 kg dummy with 600 Newton’s of force to get it to start moving and maintain a force of 475 to keep it moving at a steady state. What are the coefficient of friction static and kinetic with the dummy on the ground .

Students in an introductory physics lab are performing an experiment with a parallel-plate capacitor made of two circular aluminum plates, each 11 cm in diameter, separated by 1.0 cm. how much charge can be added to each of the plates before a spark jumps between the two plates? for such flat electrodes, assume that value of 3×106n/c of the field causes a spark.