11_Dynamics 11ed Manual - h above the ground If the...

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Engineering Mechanics - Dynamics Chapter 12 Problem 12–17 Two particles A and B start from rest at the origin s = 0 and move along a straight line such that a A = ( at b ) and a B = ( ct 2 d ), where t is in seconds. Determine the distance between them at t and the total distance each has traveled in time t . Given: a 6 ft s 3 = b 3 ft s 2 = c 12 ft s 3 = d 8 ft s 2 = t 4s = Solution: d v A d t at b = v A at 2 2 bt = s A at 3 6 bt 2 2 = d v B d t ct 2 d = v B ct 3 3s dt = s B ct 4 12 s dt 2 2 = Distance between A and B d AB at 3 6 bt 2 2 ct 4 12 s dt 2 2 + = d AB 46.33 m = Total distance A and B has travelled. D at 3 6 bt 2 2 ct 4 12 s + dt 2 2 = D 70.714 m = Problem 12–18 A car is to be hoisted by elevator to the fourth floor of a parking garage, which is at a height
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Unformatted text preview: h above the ground. If the elevator can accelerate at a 1 , decelerate at a 2 , and reach a maximum speed v , determine the shortest time to make the lift, starting from rest and ending at rest. Given: h 48 ft = a 1 0.6 ft s 2 = a 2 0.3 ft s 2 = v 8 ft s = Solution: Assume that the elevator never reaches its maximum speed. Guesses t 1 1 s = t 2 2 s = v max 1 ft s = h 1 1 ft = Given v max a 1 t 1 = 9...
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This note was uploaded on 08/16/2011 for the course EGN 3321 taught by Professor Christianfeldt during the Spring '08 term at University of Central Florida.

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