During the construction of a high-rise building, a worker accidentally dropped h
ID: 2846230 • Letter: D
Question
During the construction of a high-rise building, a worker accidentally dropped his portable electric screwdriver from a height of 400 ft. After t sec, the screwdriver had fallen a distance of s = 16t2 ft. (a) How long did it take the screwdriver to reach the ground? Incorrect: Your answer is incorrect. sec (b) What was the average velocity of the screwdriver between the time it was dropped and the time it hit the ground? ft/sec (c) What was the velocity of the screwdriver at the time it hit the ground? ft/sec
During the construction of a high-rise building, a worker accidentally dropped his portable electric screwdriver from a height of 400 ft. After t sec, the screwdriver had fallen a distance of s = 16t2 ft. (a)How long did it take the screwdriver to reach the ground? Incorrect: Your answer is incorrect. sec (b) What was the average velocity of the screwdriver between the time it was dropped and the time it hit the ground? ft/sec (c) What was the velocity of the screwdriver at the time it hit the ground? ft/sec How long did it take the screwdriver to reach the ground? What was the average velocity of the screwdriver between the time it was dropped and the time it hit the ground? What was the velocity of the screwdriver at the time it hit the ground?Explanation / Answer
a]. i/2at^2=400ft
1/2*32.2*t^2=400
16.6*t^2=400
t^2=400/16.6=24.093
t=4.90 sec
b],average velocity is vf+vi/2=[32.2*4.90+0]/2=79.032 ft/sec
c].velocity of screw driver at hitting time is 32.2*4.90=158.06 ft/sec
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