A 3000-lb automobile starts from rest and travels 1200 ft during a performance test. The motion of the automobile is defined by the relation12,000 ln(cosh 0.03 x = t), where x and t are expressed in feet and seconds, respectively. The magnitude of the aerodynamic drag is D = 0.01v2, where D and v are expressed in lb and ft/s, respectively. Determine the power dissipated by the aerodynamic drag when

(a) t = 10 s,

(b) t = 15s.