Question

11. If you want to account for air friction, you can use the principles of fluid mechanics (which you should take in a later semester) to calculate the terminal (maximum) velocity for which the drag force exactly opposes the gravitational force and prevents the falling object from further acceleration. If the falling wrench has a terminal velocity of 155 ft/s, what is the kinetic energy of the wrench? a) 187 ft lbr b) 1169 ft lbr c) 1683 ft lbr d) 421 ft lbr e) 748 ft-lb 12. If the wrench achieves terminal velocity before it hits the ground, how muclh energy did the wrench lose to air friction before it hit the ground? a) 869 ft.lbr b) 953 ft lbr c) 855 ft lbr d) 664 ft lbr e) 472 ft lb 13. If the duration of the impact of the wrench hitting the ground is 0.1 s, what is the average force of the wrench on the ground? a) 95 lbr b) 68 lbr c) 44 lbr d) 125 lbr e) 24 lbr

Answer 1