A football coach paces back and forth along the sidelines during a close rivalry game. the diagram below shows several of the coach's positions and various times. At each marked positions, the coach makes a u-turn and moves the opposite direction. In other words, the coach moves from position a to b to c to d. (Could someone please explain this. Thank you)

The air in an automobile tire with a volume of 2.60 ft3 is at 70°f and 21 psig. determine the amount of air that must be added to raise the pressure to the recommended value of 30 psig. assume the atmospheric pressure to be 14.6 psia and the temperature and the volume to remain constant. the gas constant of air is ru = 53.34ft⋅lbflbm⋅r(1 psia144 lbf/ft2) = 0.3704 psia⋅ft3lbm⋅r the amount of air that must be added to raise the pressure is lbm