Question

UTEP-CE 1301 Dec 7, 2017 Calculations (80 points total, 10 points/each). Choose the NEAREST answer 8. My friend David runs an antenna tower service company, and in a couple of weeks, he needs to perform some it- i700 maintenance at the esmasssb maintenance at the top of a tower that is 1700 ft tall (yikes!). If he carried a PE mg h 0.5 lb wrench to the top of the tower, how much potential energy does the wrench have (relative to the ground)? a) 1701 ft-lb b) 2127 ft lbr c) 1276 ft-lb d) 2552 ft-lbr e) 831 ft lb 9. If he dropped the wrench from the top of the tower, neglecting air friction, what would be its speed just before it hit the ground? a) 331 ft/s b) 53 f/s c) 32 f/s d) 117 ft/s e) 893 ft/s 10. Neglecting air friction, how long would the wrench fall? a) 10.3 s b) 2.4 s c) 7.9 s d) 52.8 s e) 331.7s

Answer 1

Potential energy P_E = mgh P_E = (0.5/32.2) (32.2) (1700) P_E = 850.lb.ft option e v^2 - u^2 = 2as V^2 - o = 2 (32.2) (1700) V^2 = 109480 v = 331 ft /sec a = acceleration s = distance u = initial velocity V = final velocity V = u + at 331 ft/sec = 0 + (32.2 ft/sec^2) t t = 331/32.2 t = 10.27sec t = 10.3 sec